Diagnostic radiology. Paediatric imaging [3 ed.] 9789350252055, 9350252058

Table of contents :
Prelims_2
Chapter-01_Technical Considerations in Pediatric Imaging
Chapter-02_Recent Advances in Pediatric Radiology
Chapter-03_Interventions in Children
Chapter-04_Imaging of Pediatric Trauma
Chapter-05_Neonatal Respiratory Distress
Chapter-06_Childhood Pulmonary Infections
Chapter-07_Chest Masses
Chapter-08_Pediatric Airway
Chapter-09_Developmental Anomalies of Gastrointestinal Tract
Chapter-10_Imaging of Anorectal Anomalies
Chapter-11_Gastrointestinal Masses in Children
Chapter-12_Hepatic and Pancreatic Masses in Children
Chapter-13_Childhood Biliopathies
Chapter-14_Congenital Anomalies of the Urinary Tract
Chapter-15_Urinary Tract Infections (Including VUR and Neuro
Chapter-16_Renal and Retroperitoneal Masses
Chapter-17_Evaluation of Female Pelvis and Testicular Abnorm
Chapter-18_Imaging of Intersex Disorders
Chapter-19_Skeletal Dysplasias
Chapter-20_Skeletal Maturity Assessment
Chapter-21_Spinal Dysraphism
Chapter-22_Imaging of Pediatric Hip
Chapter-23_Benign Bone and Soft Tissue Tumors & Conditions
Chapter-24_Pediatric Malignant Bone and Soft Tissue Tumors
Chapter-25_Congenital Brain Anomalies
Chapter-26_Hypoxic-Ischemic Encephalopathy
Chapter-27_Cranial Sonography
Chapter-28_Inflammatory Diseases of the Brain
Chapter-29_Pediatric Brain Tumors
Chapter-30_Metabolic Disorders of the Brain
Index_2

Citation preview

Diagnostic Radiology Paediatric Imaging

PIONEERS OF AIIMS-MAMC-PGI IMAGING COURSE SERIES

Manorama Berry

Sudha Suri

Veena Chowdhury

PAST EDITORS

Sima Mukhopadhyay

Sushma Vashisht

AIIMS-MAMC-PGI IMAGING SERIES

Diagnostic Radiology Paediatric Imaging THIRD EDITION

Editors Arun Kumar Gupta MD MAMS Professor and Head Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar, New Delhi, India

Veena Chowdhury MD Director Professor and Head Department of Radiodiagnosis Maulana Azad Medical College New Delhi, India

Niranjan Khandelwal MD DNB FICR Professor and Head Department of Radiodiagnosis PGIMER, Chandigarh, India

Associate Editors Ashu Seith Bhalla MD Associate Professor Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar, New Delhi, India

Sanjay Thulkar MD Associate Professor Department of Radiodiagnosis (IRCH) All India Institute of Medical Sciences Ansari Nagar, New Delhi, India

®

JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD New Delhi • St Louis • Panama City • London

Published by Jaypee Brothers Medical Publishers (P) Ltd Corporate Office 4838/24, Ansari Road, Daryaganj, New Delhi 110 002, India Phone: +91-11-43574357, Fax: +91-11-43574314 Offices in India • • • • • • • • • •

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Overseas Offices • North America Office, USA, Ph: 001-636-6279734 e-mail: [email protected], [email protected] • Central America Office, Panama City, Panama, Ph: 001-507-317-0160 e-mail: [email protected], Website: www.jphmedical.com • Europe Office, UK, Ph: +44 (0) 2031708910 e-mail: [email protected] Diagnostic Radiology: Paediatric Imaging © 2011, Jaypee Brothers Medical Publishers All rights reserved. No part of this publication should be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the editors and the publisher. This book has been published in good faith that the material provided by contributors is original. Every effort is made to ensure accuracy of material, but the publisher, printer and editors will not be held responsible for any inadvertent error(s). In case of any dispute, all legal matters are to be settled under Delhi jurisdiction only.

First Edition: Second Edition: Third Edition:

1997 2004 2011

ISBN 978-93-5025-205-5 Typeset at Printed at

JPBMP typesetting unit

CONTRIBUTORS Ajay Garg MD Assistant Professor Department of Neuroradiology All India Institute of Medical Sciences Ansari Nagar New Delhi, India

Ashu Seith Bhalla MD Associate Professor Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar New Delhi, India

Akshay Kumar Saxena MD Associate Professor Department of Radiodiagnosis PGIMER, Chandigarh, India

Atin Kumar MD MNAMS DNB Assistant Professor Department of Radiodiagnosis Trauma Centre All India Institute of Medical Sciences Ansari Nagar, New Delhi, India

Alpana Manchanda MD Professor Department of Radiodiagnosis Maulana Azad Medical College New Delhi, India Amar Mukund MD Pool Officer Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar, New Delhi, India Anjali Prakash DMRD DNB MNAMS Professor Department of Radiodiagnosis Maulana Azad Medical College New Delhi, India Anju Garg MD Director Professor Department of Radiodiagnosis Maulana Azad Medical College New Delhi, India Ankur Gadodia MD DNB FRCR Senior Resident Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar, New Delhi, India Arun Kumar Gupta MD MNAMS Professor and Head Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar, New Delhi, India

Deep N Srivastava MD MNAMS MBA

Professor Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar, New Delhi, India Gaurav S Pradhan DMRD DNB Professor Department of Radiodiagnosis Maulana Azad Medical College New Delhi, India Gurpreet Singh Gulati MD Assistant Professor Department of Cardiac Radiology Cardio-Thoracic Centre All India Institute of Medical Sciences Ansari Nagar, New Delhi, India Jyoti Kumar MD Associate Professor Department of Radiodiagnosis Maulana Azad Medical College New Delhi, India Kushaljit Singh Sodhi Assistant Professor Department of Radiodiagnosis PGIMER, Chandigarh, India Mahesh Prakash Assistant Professor

Department of Radiodiagnosis PGIMER, Chandigarh, India Manisha Jana MD DNB FRCR Senior Resident Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar, New Delhi, India Naveen Kalra MD Associate Professor Department of Radiodiagnosis PGIMER, Chandigarh, India Niranjan Khandelwal MD DNB FICR Professor and Head Department of Radiodiagnosis PGIMER, Chandigarh, India P Singh Additional Professor Department of Radiodiagnosis PGIMER, Chandigarh, India Raju Sharma MD MNAMS Additional Professor Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar, New Delhi, India Rashmi Dixit MD Professor Department of Radiodiagnosis Maulana Azad Medical College New Delhi, India Sanjay Sharma MD FRCR DNB Associate Professor Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar, New Delhi, India Sanjay Thulkar MD Associate Professor Department of Radiodiagnosis (IRCH) All India Institute of Medical Sciences Ansari Nagar, New Delhi, India

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Diagnostic Radiology: Paediatric Imaging

Sanjiv Sharma MD Professor and Head Department of Cardiac Radiology Cardio-Thoracic Centre All India Institute of Medical Sciences Ansari Nagar, New Delhi, India Sapna Singh MD DNB MNAS Associate Professor Department of Radiodiagnosis Maulana Azad Medical College New Delhi, India Shailesh B Gaikwad MD Additional Professor Department of Neuroradiology

All India Institute of Medical Sciences Ansari Nagar New Delhi, India Shivanand Gamanagatti MD MNAMS Assistant Professor Department of Radiodiagnosis Trauma Centre All India Institute of Medical Sciences Ansari Nagar, New Delhi, India Smriti Hari MD Assistant Professor Department of Radiodiagnosis All India Institute of Medical Sciences Ansari Nagar, New Delhi, India

Sumedha Pawa MD Director Professor Department of Radiodiagnosis Maulana Azad Medical College New Delhi, India Veena Chowdhury MD Director Professor and Head Department of Radiodiagnosis Maulana Azad Medical College New Delhi, India Vivek Gupta MD Assistant Professor Department of Radiodiagnosis PGIMER, Chandigarh, India

PREFACE TO THE THIRD EDITION The first edition of diagnostic radiology on Paediatric Imaging was published in 1997, while the second edition followed in 2004. The ever-evolving field of radiology and our commitment to our readers has motivated us to publish the third edition now. Rapid advances are taking place in the field of imaging. This results in the need for re-evaluating and redefining the role of a modality in different clinical scenarios. Coupled to this, particularly in paediatric radiology is the need for ensuring patient safety. The industry has made significant attempts to minimize radiation exposures in imaging and this is pre-requisite that cannot be over-emphasized in children. Paediatric radiology is already a well-established subspecialty in the West, but in the developing world due to the paucity of trained radiologists in proportion to our population, every practicing radiologist needs to be aware of the special needs and disease entities in children. The third edition of the book has been designed to include current recommendations, guidelines and existing knowledge on the subject. The content of all chapters has been updated, while some have been significantly restructured. New chapters have also been added. It is our earnest hope that our readers will find this text informative and that it will aid in their learning process and daily practice. We wish to thank all the contributors from the institutions, i.e. All India Institute of Medical Sciences, New Delhi; Maulana Azad Medical College, New Delhi and Postgraduate Institute of Medical Education and Research, Chandigarh for their efforts in updating this edition. We would also like to express our sincere appreciation to Shri Jitendar P Vij, Chairman and Managing Director, Mr Tarun Duneja (Director-Publishing), Mr Subrato Adhikary (Author Co-ordinator), Mrs Samina Khan (PA to Director-Publishing) and other staff of M/s Jaypee Brothers Medical Publishers (P) Ltd, for their professionalism and dedication towards publication of this edition. Arun Kumar Gupta Veena Chowdhury Niranjan Khandelwal

PREFACE TO THE FIRST EDITION If we are to reach real peace in this world and we are to carry on real war against war; we shall have to begin with children MK Gandhi Just as paediatrics is now justifiably recognized as a specialized area of medical practice, so has paediatric radiology, in recent years gained recognition as a specialized branch of general radiology requiring specific knowledge of the diseases of the young. Children are not merely “little people” or “young adults”, nor are the disorders to which they are particularly susceptible, merely variants of the diseases of adult life. The paediatric radiologist therefore must deal with many disorders, some of which are encountered only in the young and others only in the newborn. This book although not a complete text on paediatric radiology, is aimed at touching upon some aspects of basic and up-to-date paediatric radiology. It covers both conventional radiology and advances in imaging. This incorporates a collaborative effort of many distinguished teachers who have contributed in their own ways giving us a unique opportunity to share the art and science of radiology. However, reader must remember the words of Dr John Caffey, the father of Paediatric Radiology “A diagnosis is not made from a single type of examination such as a radiograph, but rather from a cluster of findings derived from history, physical examination and laboratory studies including a radiograph”. Reader must therefore always remember the basic rule to interpret radiological features in the background knowledge of clinical and biochemical information. Our goal in this book has been to be concise, relevant and reader-friendly. We hope the readers will find it useful. We wish to take this opportunity to thank Prof K Subbarao, Dr Ashok Khurana and our faculty colleagues from AIIMS, MAMC and PGIMER, for their active support, coordination and timely submission of the manuscripts. We also express our sincere thanks to the publishers M/s Jaypee Brothers Medical Publishers (P) Ltd for timely publication of this volume in the series of AIIMS-MAMC-PGI Imaging Courses in Diagnostic Radiology. Manorama Berry Sudha Suri Veena Chowdhury Arun Kumar Gupta Sudha Katariya

CONTENTS SECTION 1—GENERAL

1. Technical Considerations in Pediatric Imaging ................................................................................. 1 Ashu Seith Bhalla, Arun Kumar Gupta, Amar Mukund Minimizing Heat Loss ........................................................................................................................................... 1 Immobilization ...................................................................................................................................................... 1 Sedation ................................................................................................................................................................. 1 Nil Per Orally (NPO) Status .................................................................................................................................. 2 Reduction of Radiation Dosage ............................................................................................................................. 2 Use of Contrast Media ........................................................................................................................................... 8

2. Recent Advances in Pediatric Radiology .......................................................................................... 11 Akshay Kumar Saxena, Kushaljit Singh Sodhi Radiation Protection ............................................................................................................................................ 11 Neuroradiology .................................................................................................................................................... 11 Thoracic Imaging ................................................................................................................................................. 12 Gastrointestinal Imaging ..................................................................................................................................... 14 Uroradiology........................................................................................................................................................ 16 Musculoskeletal Imaging ..................................................................................................................................... 16

3. Interventions in Children ................................................................................................................... 19 Part A—Vascular Interventions ....................................................................................................................... 19 Gurpreet Singh Gulati, Sanjiv Sharma Introduction ......................................................................................................................................................... 19 Techniques ........................................................................................................................................................... 20 Procedures ........................................................................................................................................................... 20 Embolization Materials and Substances .............................................................................................................. 21 Angioplasty.......................................................................................................................................................... 27 Thrombolysis ....................................................................................................................................................... 30 Foreign Body Removal ........................................................................................................................................ 30 Part B—Nonvascular Interventions ................................................................................................................ 32 Amar Mukund, Ashu Seith Bhalla, Shivanand Gamanagatti Patient Evaluation ................................................................................................................................................ 32 Sedation and Anesthesia ...................................................................................................................................... 32 Basic Procedures ................................................................................................................................................. 32 Thoracic Interventions ......................................................................................................................................... 33 Gastrointestinal Interventions ............................................................................................................................. 33 Genitourinary Interventions ................................................................................................................................ 36

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4. Imaging of Pediatric Trauma............................................................................................................. 39 Shivanand Gamanagatti, Atin Kumar Imaging Methods ................................................................................................................................................. 39 SECTION 2—CHEST

5. Neonatal Respiratory Distress ........................................................................................................... 57 Akshay Kumar Saxena, Kushaljit Singh Sodhi Medical Causes of Neonatal Respiratory Distress .............................................................................................. 57

6. Childhood Pulmonary Infections ...................................................................................................... 68 Jyoti Kumar Introduction ......................................................................................................................................................... 68 Pneumonia ........................................................................................................................................................... 68 Tuberculosis (TB) ................................................................................................................................................ 78 Fungal Infections ................................................................................................................................................. 81 Parasitic Infestations ........................................................................................................................................... 84 Pulmonary Infections in HIV-positive Children .................................................................................................. 84

7. Chest Masses ....................................................................................................................................... 87 Sanjay Thulkar, Arun Kumar Gupta Lung Masses ........................................................................................................................................................ 87 Mediastinal Masses ............................................................................................................................................. 91 Chest Wall Masses ............................................................................................................................................... 96

8. Pediatric Airway ................................................................................................................................. 99 Ashu Seith Bhalla Upper Airway Obstruction ................................................................................................................................ 100 Acute Obstruction .............................................................................................................................................. 101 Chronic Obstruction .......................................................................................................................................... 101 Lower Airway Obstruction ................................................................................................................................ 104 SECTION 3—GASTROINTESTINAL AND BILIARY TRACT, LIVER AND PANCREAS

9. Developmental Anomalies of Gastrointestinal Tract ..................................................................... 120 Alpana Manchanda, Sumedha Pawa Imaging Modalities ............................................................................................................................................ 120 Esophagus .......................................................................................................................................................... 121 Stomach ............................................................................................................................................................. 125 Developmental Obstructive Defects .................................................................................................................. 125

Contents

xiii

Duodenum ......................................................................................................................................................... 128 Small Bowel ...................................................................................................................................................... 130 Large Bowel ...................................................................................................................................................... 138

10. Imaging of Anorectal Anomalies ..................................................................................................... 144 Arun Kumar Gupta ARA in Males .................................................................................................................................................... 147 ARA in Females ................................................................................................................................................ 149

11. Gastrointestinal Masses in Children ............................................................................................... 154 Arun Kumar Gupta Plain Radiographs .............................................................................................................................................. 154 Contrast Studies ................................................................................................................................................. 154 Ultrasonography ................................................................................................................................................ 154 Computed Tomography ..................................................................................................................................... 154 Magnetic Resonance Imaging ........................................................................................................................... 154 Esophageal Masses in Children ......................................................................................................................... 154 Gastric Masses in Children ............................................................................................................................... 155 Neoplastic Masses ............................................................................................................................................. 157 Bezoars .............................................................................................................................................................. 159 Small Bowel Masses in Children ...................................................................................................................... 159 Neoplastic Masses ............................................................................................................................................. 160 Mesenteric Masses in Children ......................................................................................................................... 164 Colonic Masses in Children .............................................................................................................................. 165

12. Hepatic and Pancreatic Masses in Children .................................................................................. 171 Akshay Kumar Saxena, Kushaljit Singh Sodhi, Naveen Kalra Imaging .............................................................................................................................................................. 171 Hepatic Masses .................................................................................................................................................. 172 Hepatoblastoma ................................................................................................................................................. 172 Hepatocellular Carcinoma (HCC) ..................................................................................................................... 173 Rhabdomyosarcoma .......................................................................................................................................... 174 Hepatic Metastases ............................................................................................................................................ 175 Infantile Hemangioendothelioma ...................................................................................................................... 175 Hemangioma ...................................................................................................................................................... 176 Mesenchymal Hamartoma ................................................................................................................................. 178 Focal Nondular Hyperplasia (FNH) and Hepatic Adenoma ............................................................................. 179 Peliosis Hepatis ................................................................................................................................................. 179 Inflammatory Lesions ........................................................................................................................................ 179 Simple Hepatic Cyst .......................................................................................................................................... 181 Polycystic Liver Disease ................................................................................................................................... 181

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Diagnostic Radiology: Paediatric Imaging

Caroli’s Disease ................................................................................................................................................. 182 Pancreatic Masses ............................................................................................................................................. 182 Islet Cell Tumors ............................................................................................................................................... 184 Solid and Papillary Epithelial Neoplasm (SPEN) (Frantz Tumor) ................................................................... 185 Mesenchymal Tumors ....................................................................................................................................... 185 Pancreatic Adenocarcinoma .............................................................................................................................. 186 Pseudocysts ....................................................................................................................................................... 186 Pancreatic Tuberculosis ..................................................................................................................................... 186

13. Childhood Biliopathies ..................................................................................................................... 189 Veena Chowdhury Definition and Pathophysiology of Cholestasis ................................................................................................ 189 Physiological Neonatal Jaundice ....................................................................................................................... 189 Etiology of Jaundice in the Neonate and Infant ................................................................................................ 189 Diagnosis of Jaundice in Infancy and Childhood .............................................................................................. 190 Neonatal Hepatitis ............................................................................................................................................. 190 Biliary Atresia (BA) .......................................................................................................................................... 191 Hepatobiliary Cystic Malformations ................................................................................................................. 196 Caroli’s Disease ................................................................................................................................................. 199 Primary Sclerosing Cholangitis (PSC) .............................................................................................................. 205 Cystic Fibrosis ................................................................................................................................................... 206 Destructive Cholangitis Associated with Langerhans’ Cell Histiocytosis ........................................................ 206 Bile Duct Paucity ............................................................................................................................................... 207 Spontaneous Perforation of CBD ...................................................................................................................... 207 Inspissated Bile Syndrome (IBS) ...................................................................................................................... 209 Jaundice in Older Children ................................................................................................................................ 209 Hepatitis ............................................................................................................................................................. 209 Chronic Active Hepatitis ................................................................................................................................... 209 Metabolic ........................................................................................................................................................... 210 Cirrhosis ............................................................................................................................................................ 210 Biliary Tract Neoplasms .................................................................................................................................... 211 Diseases of the Gallbladder ............................................................................................................................... 212 SECTION 4—GENITOURINARY

14. Congenital Anomalies of the Urinary Tract ................................................................................... 216 Smriti Hari, Arun Kumar Gupta Introduction ....................................................................................................................................................... 216 Abnormalities of Kidney ................................................................................................................................... 219 Anomalies of the Ureter .................................................................................................................................... 227 Anomalies of the Urinary Bladder .................................................................................................................... 230 Abnormalities of the Urethra ............................................................................................................................. 233

Contents

xv

15. Urinary Tract Infections (Including VUR and Neurogenic Bladder) .......................................... 237 Kushaljit Singh Sodhi, Akshay Kumar Saxena

16. Renal and Retroperitoneal Masses ................................................................................................. 248 Anju Garg Imaging .............................................................................................................................................................. 248 Renal Masses ..................................................................................................................................................... 249 Wilms’ Tumor (Nephroblastoma) ...................................................................................................................... 249 Nephroblastomatosis ......................................................................................................................................... 254 Mesoblastic Nephroma (Bolande’s Tumor) ...................................................................................................... 254 Clear Cell Sarcoma ............................................................................................................................................ 256 Rhabdoid Tumor ................................................................................................................................................ 256 Renal Cell Carcinoma ....................................................................................................................................... 256 Multilocular Cystic Renal Tumor ...................................................................................................................... 257 Angiomyolipoma ............................................................................................................................................... 257 Ossifying Renal Tumor of Infancy .................................................................................................................... 258 Metanephric Adenoma (Nephrogenic Adenofibroma, Embryonal Adenoma) .................................................. 259 Lymphoma ......................................................................................................................................................... 259 Leukemia ........................................................................................................................................................... 260 Primary Neurogenic Tumors of the Kidney ...................................................................................................... 260 Cystic Diseases of the Kidney ........................................................................................................................... 261 Adrenal Masses ................................................................................................................................................. 261 Neuroblastoma ................................................................................................................................................... 261 Ganglioneuroblastoma ....................................................................................................................................... 265 Ganglioneuroma ................................................................................................................................................ 265 Pheochromocytoma ........................................................................................................................................... 265 Adrenal Cortical Tumors ................................................................................................................................... 266 Adrenal Hemorrhage ......................................................................................................................................... 268 Adrenal Cysts .................................................................................................................................................... 268 Primary Retroperitoneal Tumors ....................................................................................................................... 268 Neurogenic Tumors ........................................................................................................................................... 268 Germ Cell Tumors ............................................................................................................................................. 269 Mesenchymal Tumors ....................................................................................................................................... 269 Retroperitoneal Lymphangioma ........................................................................................................................ 270 Lymph Node Masses ......................................................................................................................................... 270 Retroperitoneal Abscess and Hematoma ........................................................................................................... 270

17. Evaluation of Female Pelvis and Testicular Abnormalities .......................................................... 274 Kushaljit Singh Sodhi, Akshay Kumar Saxena Anomalies of the Female Pelvis ........................................................................................................................ 276 Pelvic Masses in Children ................................................................................................................................. 277 Nongynecologic Pelvic Masses ......................................................................................................................... 281

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Extratesticular Tumors ...................................................................................................................................... 290 Adrenal Rests .................................................................................................................................................... 291

18. Imaging of Intersex Disorders ......................................................................................................... 295 Sanjay Sharma, Arun Kumar Gupta Introduction ....................................................................................................................................................... 295 Classification of Intersex ................................................................................................................................... 297 Clues to the Diagnosis ....................................................................................................................................... 305 SECTION 5—MUSCULOSKELETAL

19. Skeletal Dysplasias ............................................................................................................................ 307 Gaurav S Pradhan Introduction ....................................................................................................................................................... 307 Terminology ...................................................................................................................................................... 307 Osteochondrodysplasias .................................................................................................................................... 308 Dysostoses ......................................................................................................................................................... 323 Idiopathic Multicentric Osteolysis .................................................................................................................... 324 Primary Disturbance of Growth ........................................................................................................................ 324 Constitutional Diseases of Bone with Known Pathogenesis ............................................................................. 324

20. Skeletal Maturity Assessment .......................................................................................................... 328 Arun Kumar Gupta Measurement of Maturity .................................................................................................................................. 328

21. Spinal Dysraphism ............................................................................................................................ 333 Raju Sharma, Ankur Gadodia Introduction ....................................................................................................................................................... 333 Classification ..................................................................................................................................................... 333 Embryology ....................................................................................................................................................... 333 Imaging Modalities ............................................................................................................................................ 334 Open Spinal Dysraphism (OSD) ....................................................................................................................... 337 Closed Spinal Dysraphism (CSD) ..................................................................................................................... 339 Split Cord Malformation (SCM) ....................................................................................................................... 346 Dorsal Dermal Sinus (DDS) .............................................................................................................................. 346 Caudal Agenesis (Caudal Regression Syndrome, CRS) .................................................................................... 348 Segmental Spinal Dysgenesis (SSD) ................................................................................................................. 348

22. Imaging of Pediatric Hip .................................................................................................................. 351 Anjali Prakash Introduction ....................................................................................................................................................... 351 Methods of Investigation ................................................................................................................................... 351

Contents

xvii

Pediatric Hip Disorders ..................................................................................................................................... 355 Developmental Dysplasia of the Hip ................................................................................................................. 356 Natural History and Pathology .......................................................................................................................... 356 Imaging in DDH ................................................................................................................................................ 356 Transient Synovitis of Hip ................................................................................................................................. 366 Legg-Calve-Perthes’ Disease ............................................................................................................................. 367

23. Benign Bone and Soft Tissue Tumors & Conditions ..................................................................... 381 Mahesh Prakash, Kushaljit Singh Sodhi Cartilaginous Tumors ........................................................................................................................................ 381 Osseous Tumors ................................................................................................................................................ 383 Fibrous Tumors .................................................................................................................................................. 385 Histiocytosis X (Langerhans Cell Histiocytosis) .............................................................................................. 385 Giant Cell Tumor ............................................................................................................................................... 386 Tumor Like Lesions ........................................................................................................................................... 386 Soft Tissue Tumors ............................................................................................................................................ 387 Fibroblastic/Myofibroblastic Tumors ................................................................................................................ 390

24. Pediatric Malignant Bone and Soft Tissue Tumors ....................................................................... 395 Manisha Jana, Ashu Seith Bhalla, Deep N Srivastava Introduction ....................................................................................................................................................... 395 Imaging Modalities ............................................................................................................................................ 395 Malignant Bone Tumors .................................................................................................................................... 397 Soft Tissue Tumors ............................................................................................................................................ 401 SECTION 6—CENTRAL NERVOUS SYSTEM

25. Congenital Brain Anomalies ............................................................................................................ 404 N Khandelwal Introduction ....................................................................................................................................................... 404 Disorders of Organization ................................................................................................................................. 404 Disorders of Histogenesis .................................................................................................................................. 414

26. Hypoxic-Ischemic Encephalopathy ................................................................................................. 419 Atin Kumar, Arun Kumar Gupta Neuroimaging in Infants with HIE .................................................................................................................... 419 Below 34 Weeks Group – The Premature Neonate ........................................................................................... 419 Above 34 Weeks Group – The Term Neonate ................................................................................................... 428 Hypoxic Ischemic Injury in Postnatal Age Group ............................................................................................. 431 Imaging Choice for Evaluation of Hypoxic-ischemic Injury ............................................................................ 432 Prediction of Clinical Outcome ......................................................................................................................... 432

xviii Diagnostic Radiology: Paediatric Imaging

27. Cranial Sonography ......................................................................................................................... 436 Rashmi Dixit, Veena Chowdhury Destructive Brain Lesions ................................................................................................................................. 441 Hydrocephalus ................................................................................................................................................... 441 Intracranial Hemorrhage .................................................................................................................................... 444 Hypoxic or Ischemic Encephalopathy ............................................................................................................... 446 Neonatal and Acquired Infections ..................................................................................................................... 449

28. Inflammatory Diseases of the Brain................................................................................................ 454 V Gupta, N Khandelwal, P Singh Introduction ....................................................................................................................................................... 454 Investigative Modalities .................................................................................................................................... 454 Bacterial Infections ............................................................................................................................................ 454 Cranial Tuberculosis .......................................................................................................................................... 457 Neurocysticercosis............................................................................................................................................. 461 Hydatid Disease ................................................................................................................................................. 464 Viral Encephalitis .............................................................................................................................................. 465 Congenital Infections ........................................................................................................................................ 468 Fungal Infections ............................................................................................................................................... 475

29. Pediatric Brain Tumors .................................................................................................................... 477 Shailesh B Gaikwad, Ajay Garg Introduction ....................................................................................................................................................... 477 Classification of Childhood Tumors Based on Topography ............................................................................. 477 Posterior Fossa Tumors ..................................................................................................................................... 477 Supratentorial Tumors ....................................................................................................................................... 482 Sellar and Suprasellar Tumors........................................................................................................................... 485 Pineal Region Masses ........................................................................................................................................ 487 Extraparenchymal Tumors ................................................................................................................................ 488 Tumors of the Orbit and Neck ........................................................................................................................... 490 Ocular Tumors ................................................................................................................................................... 490 Retrobulbar Orbital Tumors .............................................................................................................................. 490 MR Spectroscopy (MRS) in Brain .................................................................................................................... 491 Nanotechnology ................................................................................................................................................. 492

30. Metabolic Disorders of the Brain .................................................................................................... 494 Sapna Singh, Veena Chowdhury Introduction ....................................................................................................................................................... 494 Metabolic Disorders .......................................................................................................................................... 495 Lysosomal Storage Disorders ............................................................................................................................ 498 Peroxisomal Disorders ...................................................................................................................................... 505

Contents

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Unclassified Leukodystrophies ......................................................................................................................... 509 Mitochondrial Disorders/Defects of the Respiratory Chain .............................................................................. 516 Disorders of Amino Acid Metabolism/Aminoacidopathies .............................................................................. 520 Organic Acidemias ............................................................................................................................................ 524 Metabolic Disorders Primarily Affecting Gray Matter ..................................................................................... 526 Disorders of Metal Metabolism......................................................................................................................... 527 Index ............................................................................................................................. 533

SECTION 1—GENERAL

chapter 1

Technical Considerations in Pediatric Imaging Ashu Seith Bhalla, Arun Kumar Gupta, Amar Mukund

Technical factors such as the ability to position the patient and expose the radiograph with the patient immobile, which are often taken for granted in adult radiography, may appear as crippling problems in pediatric radiography. For this reason and because of the importance of minimizing radiation to the child, special attention must be paid to certain technical points. These will be discussed under the following five broad groups: I. Minimizing heat loss II. Immobilization III. Sedation IV. Reduction of radiation dosage V. Use of contrast media

MINIMIZING HEAT LOSS Neonates and infants lose body heat rapidly, the risk of hypothermia being greatest in the premature baby with little subcutaneous fat. Local warmth may be obtained by special table-top heating cradles, but the most convenient way of avoiding heat loss is to maintain a room temperature of about 27°C in room. A room thermometer is an important piece of equipment. Enhanced humidity is not normally required for the duration of an X-ray examination.1 IMMOBILIZATION Atraumatic immobilization is essential in order to ensure proper positioning and to minimize patient motion. Newborn babies and small infants need only soft sandbags and adhesive tape to stop movement. Towels and sheets can also be used to tightly wrap babies. Older, stronger children require wrapping on immobilization boards in addition to tape and sandbags. Special X-ray equipment is available which is designed specifically for the examination of infants and children. The essential factors for an immobilization device are (1) absence of artifacts, (2) safety, (3) no disturbance of the patient’s sedation, and (4) ease of handling. It is not always possible to accommodate older children on such apparatus. Cradle holding devices are provided which enable the infant to be rotated in relation to the tabletop. When this type of equipment is not available, views such as the prone shoot through swallow for tracheoesophageal fistula may be obtained by using a device such as the Charteris baby holder inverted on the step of an up-right adult screening table.1-3

SEDATION One fundamental technical component for imaging is the need for the child to remain motionless during the duration of imaging. Babies and infants under 6 months of age will often sleep after a feed and may not need sedation unless they are known to be restless, or the procedure is painful. Adjunctive measures such as sleep deprivation can also be useful. In older children verbal reassurance may be sufficient. Venous access produces less disturbance if a cannula is put in place after the area has been treated with a topical gel. Two possible area can be prepared about 30 mins before injection. Small gage needles are used, often 22 to 25 gage. Warming of contrast medium makes injection through fine needles easier and less painful.1,4,5 Sedation, however, is often necessary, especially for procedures like MRI due to its long duration, and for interventions due to the pain involved. Once it is deemed that both the procedure and sedation are necessary, every effort must be made to provide safety for the child. Even if the radiologist is not directly responsible for the sedation procedure, he or she must expedite the procedure in order to minimize the length of sedation. The timing of sedation and of the procedure need careful coordination.1,5 Monitoring the patient in the radiology suite is not an easy task for the clinicians. Observing children from the CT or MRI control room through a glass window is much more difficult for the clinician than direct observation at the bedside and increases their reliance on monitoring devices. Hence, adequate monitoring devices should be available. Pulse oximetry is commonly used during sedation. Monitoring is further complicated during MRI because the scanner generates strong static, radio-frequency and time varied magnetic fields which interfere with the monitoring devices. New nonferromagnetic monitors and cables have been deviced which are safe and reliable within the scanning suite. Standard ferromagnetic monitors if used need to be placed outside the magnetic field or carefully shielded.4,5 The radiology suite is a less than ideal environment for dealing with respiratory arrest or cardiovascular collapse. Hence, the most important prerequisite to sedation is the availability of adequate equipment for resuscitation and personnel experienced in managing sedation complications. If the radiology suite is not equipped with wall outlets for oxygen and suction, portable oxygen cylinders and

2

Section 1 ™ General

suction apparatus should be available. Also, a cart with resuscitation drugs, defibrillator, and age and size appropriate equipment for different age groups and body sizes for purpose of oxygen administration and intubation are absolutely essential.4,5 Risk factors must be taken into consideration before planning sedation. If the child’s condition is tenuous enough for sedation to be a significant risk, precautionary measures like securing the airway should be taken before the child arrives in the radiology department. Knowledge of both the past and the present medical history is equally important.

NIL PER ORALLY (NPO) STATUS Aspiration is a significant concern in sedated children and NPO guidelines should be as stringent as those in children undergoing general anaesthesia. Guidelines recommended by American Academy of Pediatrics Committee on Drugs (AAPCOD) are as follows: clear liquids are allowable up to 2 hours before the procedure for any age; semisolid liquid (including breast milk) and solid foods are acceptable for up to 4 hours for children less than 6 months, 6 hours for children 6 to 36 months old and 8 hours for older children. Whenever possible these recommendations must be followed. Bowel obstruction or ileus are other factors that increase the risk of aspiration because they delay gastric emptying. In these patients, nasogastric suction of gastric contents should be performed and agents given that promote gastric emptying, such as metoclopramide. The actual risk of aspiration in children undergoing diagnostic imaging, is unknown, but it is probably quite low. In one recent report, aspiration of gastric contrast was present in no more than 4 percent of children undergoing CT scan examination in a setting of trauma.4,6 The practice of administering oral contrast material in children before sedation for abdominal CT is controversial. At some institutions, the practice of administering an enteric contrast material before sedation is being discouraged because it violates the “nothing by mouth” status that is otherwise strictly enforced before sedation. However, recent studies have indicated that oral contrast appears to be safe when using the sedation drugs like chloral hydrate and propofol. Further study of the safety of this practice is required.7 Pharmacological Agents Several different agents have been successfully used for sedation of children for imaging studies. The choice of the agent depends on availability, local expertise and patient risk factors. The route of administration could be oral or parenteral. Intravenous route has the advantage of faster onset and reliable titration of dose. Other non-parenteral routes include the intranasal or rectal route. The most commonly used sedative agents belong to one of the three classes of drugs: 1. Barbiturates, 2. Benzodiazepines, or 3. Narcotics. The most often used barbiturate is pentobarbital. Others being methohexital and thiopental sodium. Pentobarbital and Quinalbarbitone are safe, effective oral agents in children under the age of

5 years. The benzodiazepines include diazepam and midazolam. Diazepam is not used routinely as a sedative for diagnostic imaging in children. Respiratory depression is the most important concern with barbiturates while vomiting is often seen with midazolam. Narcotics are commonly used as an adjunct to other sedative agents in situations where pain control is desirable in addition to sedation.4,5 Besides these three groups of drugs, other commonly used agents include triclofos, chloral hydrate, propofol, ketamine and a combination of meperidine (Demerol), chlorpromazine (Phenargan) and promethazine (Thorazine) {also known as DPT, or the “lytic” cocktail}, injected intramuscularly. Triclofos (pedicloryl) is a good sedative agent which can be used orally to sedate infants and children 70

40 50 60 70 80 100-120 ≥ 140

60 70 80 100 120 140-150 ≥ 170

tion of iodine achieved within plasma and urine, economic factors, and safety factors.

Figs 1.4A and B: Chest CT at 240 mA (A) and at 77 mA (B). Image quality is comparable while radiation dose in B is less than one-third of that in A

parameters (tube voltage, tube current, slice thickness, collimation and pitch) optimized as per the use. The important point to remember is that different manufacturers use different techniques for dose modulation so the user should know about the system’s characteristics before trying to attempt any change in scanning parameters.39 Any changes should be performed using appropriate (weight range) phantoms. Recently dual energy CT scanners have been introduced which are faster and have ability to provide greater information about tissue composition than obtained by single energy scanners. Although not much is known about its use in pediatric cases, however with dual energy scanners non contrast CT scans are not needed as contrast media can be subtracted, and the patient is spared the radiation dose of a second scan.

USE OF CONTRAST MEDIA Contrast media available for intravenous (IV) use in radiography are categorized as high-osmolality contrast media (HOCM), lowosmolality contrast media (LOCM) and isosmolar contrast media (IOCM). Considerations in choice amongst these are the concentra-

High Osmolality Contrast Media HOCM have an iodine content ranging from 280 to 480 mg/mL and an osmolality range from 1400 to 2500 mOsm/kg. Dosage of contrast material is based upon grams of iodine administered in relation to body mass. It is appropriate to use a dosage of approximately 300 mg of iodine per kilogram. This represents approximately 1.0 mL/kg in the most commonly used forms of diatrizoate or iothalamate. The total dose for excretory urography or for CT is usually 2.0 mL/kg in children or 3.0 mL/kg in the newborn. Speed of injection is important for the resultant plasma concentration of contrast material. After rapid injection there is an increase in serum osmolality within 3 minutes, a decrease in serum sodium concentration, and an increase in heart rate. The osmotic effect is particularly significant in young infants. A mean increase of 3 percent in serum osmolality is observed in adults. Excretion occurs rapidly by renal glomerular filtration. Because of a high osmotic load, these contrast media also produce diuresis, opposing tubular resorption.38 Low Osmolality Contrast Agents LOCM have an iodine content ranging from 128 to 320 mg/mL and an osmolality range from 290 to 702 mOsm/kg. Agents with low iodine content are most suitable for intra-arterial digital subtraction arteriography. Those with iodine content of 240 to 300 mg/mL are used for excretory urography, venography, venous injection digital subtraction arteriography, and bolus IV enhancement for CT scans. The contrast media with high iodine content, 320 to 370 mg/mL, are used for aortography and selective arteriography. Iso Osmolar Contrast Agents IOCM have an iodine content ranging from 270 to 320 mg/mL and an osmolality of 290 mOsm/kg. Initial reports showed that the IOCM reduces the risk of contrast induced nephropathy (CIN) in patients with deranged renal parameters. However recently various meta-analysis of randomized control trials have shown that there is no statistically significant

Chapter 1 ™ Technical Considerations in Pediatric Imaging

reduction in CIN associated with iodixanol as compared to LOCM.39,40 Hence with this equivocal kind of reports IOCM offers no significant advantage over LOCM. Unlike HOCM, LOCM and IOCM have little or no effect on serum osmolality, serum sodium, vasodilation, haemodilution, red blood cell morphology, or vascular permeability. There is little or no effect on the blood-brain barrier, fewer electrocardiographic changes, and fewer alterations in myocardial contractility, cardiac output, and left ventricular, pulmonary artery, and aortic pressures. There is less endothelial damage, and lower release or activation of vasoactive substances including complement activation, histamine release, and acetylcholinesterase inhibition. Diminished effects on coagulation pathways have been demonstrated. These effects are attributed to the lower osmolality and the reduced chemotactic effect of the molecules. Of importance is reduction in the nephrotoxic effect noted with HOCM. Hence, there are definite advantages to adoption of LOCM. A major consideration is degradation of the resulting examination resulting from pain, heat or vomiting with HOCM.38 Performing a multiphasic CT scans in neonate and infants may be challenging, as the IV cannula is of smaller gage limiting the injection rate of power injector, moreover only small amount of IV contrast can be used depending on the weight of the child. These situations may be handled by (i) using bolus tracking and saline chasing technique and (ii) large bore cannula.41,42 An injection rate of 2-3 ml/sec is safe and provides good results.40 Although there is no consensus, but contrast may be administered using central venous line with a maximum injection rate of 2 ml/sec.41

MR Contrast Agents The most commonly used contrast agents are paramagnetic substances and amongst these Gadolinium diethylenetriamine penta-acetic acid (Gd DTPA) dimeglumine is most frequently used. Gd DTPA is excreted by glomerular filtration with 90 percent excreted within 24 hours. Rapid renal clearance, and low toxicity are important features of this contrast material. The clinical dose of Gd DTPA is 0.1 mmol/kg. It has an osmolality of 1,900 mOsm/ kg. However, the high osmolality is of little importance because of the small volume administered.38,43 Although gadolinium-enhanced MR imaging was once considered one of the safer imaging procedures, but recently there has been a significant concern regarding nephrogenic systemic fibrosis (NSF) associated with gadolinium based contrast agents. The identified risk factors associated with development of NSF include - administration of a high dose of gadolinium-based contrast agent, acute or chronic renal failure, venous thrombosis and coagulopathy and vascular surgery.44,45 Some additional guiding principles for use of contrast in the neonates are: 1. Use warm contrast for maintenance of body temperature. 2. Use iso-osmolar+ve, non-ionic contrast in most instances. 3. When giving oral or rectal contrast, use low-osmolar, non-ionic agents instead of barium to avoid barium contamination of the peritoneal cavity.

9

4. Do not give contrast blindly; oral contrast may be aspirated, and rectal contrast may get into peritoneal cavity via a perforation. Even in the intact bowel, the contrast may not progress distally as quickly as predicted and therefore may lead to unnecessary radiographs. 5. Be judicious in the volume of contrast administered. Renal function in neonates is less than in babies over one month and age, therefore excretion of contrast may be delayed. 6. Gadolinium is the preferred contrast agent for magnetic resonance imaging. However, it should be used with a caution.43,44,45 In conclusion the aim of all departments and radiologists dealing with pediatric imaging should be to achieve a diagnostically adequate radiograph or examination, with minimum radiation exposure and discomfort to the child. This goal can only be achieved if the radiologists and technicians in charge are committed to quality control programs, and are aware of the necessity for radiation protection in children.

REFERENCES 1. Levick RK, Spriqq A. In Whitehouse GH, Worthington BS (Eds): Pediatric Radiology in Techniques in Diagnostic Imaging (3rd edn) 1996; 389-404. 2. Tani S, Mizuno N, Abe S. Availability and improvement of a vacuum-type immobilization device in pediatric CT. Abstract in English on pubmed. Nippon Hoshasen Gijutsu Gakkai Zasshi 2002; 58(8):1073-79. 3. Bontrages KL. Pediatric Radiography in Textbook of Radiographic Positioning and Related Anatomy (5th edn). St Louis: Mosby 2001; 629-64. 4. Frush DP, Bisset GS. Sedation of children for emergency imaging. RCNA 1997; 35(4):789-97. 5. Chudnofsky C, Krauss B, Brustowic Z (Eds): Sedation for Radiologic Imaging in Pediatric Procedural Sedation and Analgesia Maryland, USA: Lippincott Williams and Wilkins 2001; 169-78. 6. Lim-Dunham JE, Narra J, Benya EC, et al. Aspiration following oral contrast administration for pediatric trauma CT scans [abstract 46]. In 82nd Scientific Assembly and Annual Meeting, Radiological Society of North America. Chicago, Radiological Society of North America 1996; 137. 7. Ziegler MA, Fricke BL, Donnelly LF. Is administration of enteric contrast matrial safe before abdominal CT in children who require sedation? Experience with chloral hydrate and pentobarbital. AJR 2003; 180(1):13-15. 8. Iwata S, Okumura A, Kato T, Itomi K, Kuno K. Efficacy and adverse effects of rectal thiamylal with oral triclofos for children undergoing magnetic resonance imaging. Brain Dev. 2006; 28(3):175-7. 9. Frush DP, Bisset GS 3rd, Hal SC. Pediatric sedation in radiology: The practice of safe sleep. AJR Am J Roentogenol 1996; 167:1381. 10. Pierce DA, Preston DL. Radiation related cancer risks at low doses among atomic bomb survivors: Radiat Res 2000; 154:178-86. 11. Slovis TL. Executive summary, ALARA Conference: Pediatric Radiology 2002; 32:221. 12. Schneider K. Radiation Protection in pediatric radiology: How important is what? In syllabus of 20th Postgraduate Course European Society of Pediatric Radiology 1997; 95-101.

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13. Protection of the patient in diagnostic radiology: Summary of the current ICRP principles, by Atomic Energy Regulatory Board: Mumbai 1987; 3-16. 14. Gonzalez L, Vano E, Ruiz MJ. Radiation dose to pediatric patients undergoing micturating cystourethography examinations and potential reduction by radiation protection optimization. Br J Radiol 1993; 68:291-95. 15. Martin CJ, Darragh CL, Mc Kenzie GA, et al. Implementation of a program for reduction of radiographic doses and result achieved through increase in tube potential. Br J Radiol 1993; 66:228-33. 16. Mooney, et al. Dose reduction in a pediatric X-ray department following optimization of radiographic technique. Br J Radiol 1998; 71:852-60. 17. Kohn MM, et al. Guidelines on Quality Criteria for Diagnostic Radiographic Images in Pediatrics. CEC Directorate General XII/ D/3, Brussels, 1996. 18. Uffmann M, Schaefer-Prokop C. Digital radiography: The balance between image quality and required radiation dose. Eur J Radiol 2009; 72(2):202-8. 19. Willis CE. Optimizing digital radiography of children. Eur J Radiol 2009; 72(2):266-73. 20. Fearon T, Vucich J. Normalized pediatric organ absorbed doses from CT examinations. AJR 1987; 148:171-74. 21. Nicholson RA, Thornton A, Akpan M. Radiation dose reduction in pediatric fluoroscopy using added filtration. Br J Radiol 1995; 68(807):296-300. 22. Bogaert E, Bacher K, Lapere R, Thierens H. Does digital flat detector technology tip the scale towards better image quality or reduced patient dose in interventional cardiology? Eur J Radiol 2009; 72(2):348-53. 23. Chida K, Inaba Y, Saito H, Ishibashi T, Takahashi S, Kohzuki M, Zuguchi M. Radiation dose of interventional radiology system using a flat-panel detector. AJR Am J Roentgenol 2009; 193(6):1680-5. 24. Shah R, Gupta AK, Rehani M. Evaluation of radiation dose to children undergoing radiological examinations and reduction of dose by protective methods. (Unpublished data) Deptt. of Radiodiagnosis, AIIMS, 2002. 25. Schneider K. Evolution of Quality assurance in pediatric radiology. Radiation Protection Dosimetry 1995; 57:119-23. 26. Fendel H, Schineider K, Bakowski C, et al. Specific principles for optimization of image quality and patient exposure in pediatric diagnostic imaging. BJR 1990; 20:91-110. 27. Fendel H. Die zehn Gebote des Strahlenshutzes bei der Rontgendiagnostikim Kindesalter. Pediatric Prax 1976; 17:339-46. 28. Fendel H, Schneider K, Schofer H, et al. Optimization in pediatric radiology: Are there specific problems for quality – assurance in pediatric radiology. Brit J Radiol 1985; 18:159-65. 29. Drury P, Robinson A. Fluoroscopy without the grid: A method of reducing the radiation dose. Br J Radiol 1980; 53(626):93-99. 30. Brenner DJ, Ellison CD. Estimated risks of radiation induced fatal cancer from pediatric CT. AJR 2001; 176:289-96.

31. Frush DP, Donnelly LF. Helical CT in children technical considerations and body applications: Radiology 1998; 209:37-48. 32. Fearon T, Vucich J. Normalized pediatric organ absorbed doses from CT examinations. AJR 1987; 148:171-74. 33. Kuhn JP, Brody AS. High resolution of CT pediatric lung disease. RCNA 2002; 40(1):89-110. 34. McCollough CH, Bruesewitz MR, Kofler JM Jr. CT dose reduction and dose management tools: Overview of available options. Radiographics 2006; 26(2):503-12. 35. Lee CH, Goo JM, Ye HJ, Ye SJ, Park CM, Chun EJ, Im JG. Radiation dose modulation techniques in the multidetector CT era: From basics to practice. Radiographics 2008; 28(5):1451-9. 36. Söderberg M, Gunnarsson M. Automatic exposure control in computed tomography – an evaluation of systems from different manufacturers. Acta Radiol 2010; 51(6):625-34. 37. Shah R, Gupta AK, Rehani M M, Pandey AK, Mukhopadhyay S. Effect of reduction in tube current on reader confidence in pediatric computed tomography. Clinical Radiology 2005; 60(2):224-31. 38. Rogalla et al. Low dose spiral CT applicability to pediatric chest imaging: Pediatr Radiol 1999; 29:565-69. 39. Gudjónsdóttir J, Ween B, Olsen DR. Optimal use of AEC in CT: A literature review. Radiol Technol 2010; 81(4):309-17. 40. Currarino G, Wood B, Mayd: In Silverman FN, Kuhn JP (Eds). Diagnostic Procedures: The Genitourinary Tract and Retroperitoneum in Caffey’s Pediatric X-Ray Diagnosis (9th edn). 1148-71, St Louis: Mosby, 1993. 41. From AM, Al Badarin FJ, McDonald FS, Bartholmai BJ, Cha SS, Rihal CS. Iodixanol Versus Low-Osmolar Contrast Media for Prevention of Contrast Induced Nephropathy: Meta-analysis of Randomized, Controlled Trials. Circ Cardiovasc Interv 2010; 3(4):351-8. 42. Heinrich MC, Häberle L, Müller V, Bautz W, Uder M. Nephrotoxicity of iso-osmolar iodixanol compared with nonionic low-osmolar contrast media: Meta-analysis of randomized controlled trials. Radiology 2009; 250(1):68-86. 43. Nievelstein RA, van Dam IM, van der Molen AJ. Multidetector CT in children: current concepts and dose reduction strategies. Pediatr Radiol. 2010 Aug;40(8):1324-44. Epub 2010 Jun 10. 44. Fleishmann D, Kamaya A. Optimal vascular and parenchymal contrast enhancement: The current state of the art. Radiol Clin North Am 2009; 47:13-26 45. Slovin TL: In Kuhn JP, Slovin TL, Halles JO (Eds). Neonatal Imaging: Overview in Caffey’s Paediatric Diagnostic Imaging (10th edn). Penn Sylvania: Mosby 2004; 15-18. 46. Prince MR, Zhang HL, Prowda JC, Grossman ME, Silvers DN. Nephrogenic systemic fibrosis and its impact on abdominal imaging. Radiographics 2009; 29(6):1565-74. 47. Juluru K, Vogel-Claussen J, Macura KJ, Kamel IR, Steever A, Bluemke DA. MR imaging in patients at risk for developing nephrogenic systemic fibrosis: Protocols, practices, and imaging techniques to maximize patient safety. Radiographics 2009; 29(1):9-22.

chapter 2

Recent Advances in Pediatric Radiology Akshay Kumar Saxena, Kushaljit Singh Sodhi

The articles dwelling upon pediatric radiology are published not only in the radiology journals but also in journals in the fields of allied specialties like pediatrics and pediatric surgery. There is no strict definition of recent advances. For an avid reader, recent advances mean the literature published in last few months (say one year); for a research worker dedicated to a particular topic, only the articles published in that context would constitute recent advances while for a general radiologist, changing trends over last few years would qualify for recent advances. Given the vast plethora of articles available in medical literature and differing needs of radiologists, it is impossible to cater to the need of all. This chapter dwells upon some of the recent trends in speciality of pediatric radiology as applicable to Indian scenario. Readers are encouraged to update their knowledge by reading the recent journals.

RADIATION PROTECTION The children are known to be at high risk for developing radiation induced malignancies. This is because the growing tissues are more radio sensitive. In addition, children have long life span available to manifest the ill effects of radiation. Hence, there is a need to keep the radiation dose to the minimum possible level in children. An Alliance for Radiation Safety in Pediatric Imaging (Image Gently campaign)1 has recently taken shape with the objective increasing awareness in the imaging community of the need to adjust radiation dose when imaging children. It started as a committee within the Society for Pediatric Radiology in late 2006 and currently encompasses 56 professional associations globally. The ultimate goal of this alliance is to change practice. The initial focus of the alliance has been CT scan as there has been dramatic global increase in number of CT scans being performed for children. The alliance website (www.imagegently.org) provides information for radiologists, parents, pediatricians, medical physicists and radiology technologists. The alliance has evoked widespread interest. Already, the website has been visited over 300,000 times, the CT protocol has been downloaded over 20,000 times and 4528 medical professionals have taken the pledge. Recently, the alliance has started targeting radiation safety pediatric interventional radiology. It has been labeled “Image Gently, Step Lightly”. It encourages the radiologists to “Step Lightly” on the fluoroscopy pedal during the pediatric interventional

procedures. It also encourages the radiologists to use ultrasound or MRI for guidance during interventional procedures. The image gently campaign has been named to the 2009 Associations Advance America Honor Roll. This award is sponsored by the American Society of Association Executives to recognize the ways non-profit associations improve the quality of life in America. Detailed guidelines are now available for reducing radiation dose during fluoroscopy, CT scan and interventional procedures in children.2-4

NEURORADIOLOGY CT scan of head is commonly performed for head trauma in children. However, very few of these patients show CT evidence of intracranial injury. Since CT scan imparts high radiation dose, it is desirable to minimize number of children who do not require CT scan after head trauma. Palchak and colleagues5 conducted a prospective observational study to derive a decision rule for identifying children at low risk for traumatic brain injuries. They enrolled 2043 children and evaluated clinical predictors of traumatic brain injury on CT scan and traumatic brain injury requiring acute intervention, defined by (i) a neurosurgical procedure (ii) antiepileptic medications for more than 1 week (iii) persistent neurologic deficits or (iv) hospitalization for at least 2 nights. CT scan was performed in 1,271 (62%) patients of which 98 (7.7%) had traumatic brain injuries on CT scan. 105 (5.1% of 2043 enrolled patients) had traumatic brain injuries requiring acute intervention. Abnormal mental status, clinical signs of skull fracture, history of vomiting, scalp hematoma (in children ≤ 2 years of age), or headache identified 97/98 (99%) of those with traumatic brain injuries on CT scan and 105/105 (100%) of those with traumatic brain injuries requiring acute intervention. Amongst the 304 (24%) children undergoing CT with none of these predictors, only 1 (0.3%) patient had traumatic brain injury on CT. This patient was discharged from the emergency department without complications. The authors concluded that absence of abnormal mental status, clinical signs of skull fracture, history of vomiting, scalp hematoma (in children ≤ 2 years of age), and headache were important factors for identifying children at low risk for traumatic brain injuries after blunt head trauma.

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Section 1 ™ General

Magnetic resonance imaging (MRI), diffusion tensor imaging (DTI) and MR spectroscopy are important constituents of evaluation of neonatal encephalopathy. Barkovich6 and colleagues performed serial MRI in 10 neonates to describe the time course of changes in different brain regions during the first 2 weeks of life. In most of the patients DTI and MR spectroscopy revealed a characteristic evolution pattern during the first 2 weeks after birth. Although, the anatomic images were normal or nearly normal on the first 2 days after birth in most patients, abnormalities were detected on DTI and spectroscopy. The parameters tended to worsen until about day 5 and then normalize, though in several patients abnormal metabolite ratios on spectroscopy persisted. During the serial scans, the areas of reduced diffusion pseudonormalized in some parts while new abnormal areas developed in other parts. Thus, the pattern of injury looked very different on serial scans. Liauw and colleagues7 evaluated the predictive value of DWI and apparent diffusion coefficient (ADC) measurements for outcome in children with perinatal asphyxia. MRI was performed in term neonates with in ten days of life because of birth asphyxia. In survivors, developmental outcome until early school age was graded as: 1) normal, 2) mildly abnormal, and 3) definitely abnormal. For analysis, category 3 and death (category 4) were labeled “adverse,” 1 and 2 were “favorable,” and 2-3 and death were “abnormal” outcome. The study demonstrated that ADC values in normal-appearing basal ganglia and brain stem correlated with outcome independent of all MR imaging findings. However, ADC values in visibly abnormal brain tissue on DWI did not show a predictive value for outcome. Another study (by Vermeulen and colleagues) which evaluated diffusion-weighted and conventional MR imaging in neonatal hypoxic ischemia reported DW imaging to be a useful additional MR tool to predict the motor outcome at 2 years. In this study, local ADC values had a limited value. Recognition of the patterns of brain damage with DW and conventional MR imaging appeared useful as a diagnostic tool. Although, ultrasound and MRI are frequently utilized for evaluation of neonatal hypoxic ischemic injury, there is striking paucity of prospective studies comparing these two modalities. Epelman and colleagues8 prospective performed ultrasound and MRI of 76 neonates and young infants (age range 1-44 days; means age 9.8 days). Both the studies were done within two hours of each other. The diagnostic accuracy of ultrasound was found to be 95.7%. The authors recommended the use of ultrasound as screening modality with emphasis on correct technique. They also recommended early MRI for mapping delineating entent of injury. Tovar-Moll F9 and colleagues utilized magnetic resonance diffusion tensor imaging and tractography in patients of callosal dysgenesis to reveal the aberrant circuit. The study group consisted of eleven patients nine of which belonged to pediatric age group. Four main findings were reported: 1. In the presence of a callosal remnant or a hypoplastic corpus callosum, fibers therein largely connect the expected neocortical regions 2. Callosal remnants and hypoplastic corpus callosum display a fiber topography similar to normal

3. At least 2 long abnormal tracts are formed in patients with defective CC: Probst bundle and a sigmoid, asymmetrical aberrant bundle connecting the frontal lobe with the contralateral occipito parietal cortex 4. Whereas the PB is topographically organized and has an ipsilateral U-connectivity, the sigmoid bundle is a long, heterotopic commissural tract. These observations suggested that when the process of corpus callosum fibers to cross the midline is hampered, some properties of the miswired fibers are maintained (such as side-by-side topography), whereas others are dramatically changed, leading to the formation of grossly abnormal white matter tracts. MRI is considered inferior to CT scan in detecting calcification. However, susceptibility weighted imaging (SWI) technique can identify calcification by using phase images. Using this technique Wu and colleagues10 were able to detect a partially calcified oligodendroglioma, multiple calcified cysticercosis lesions, and multiple physiologic calcifications in a single patient. The authors concluded that SWI filtered phase images can identify calcifications as well as CT scan. Wang11 and colleagues evaluated serial MRI changes compared to clinical outcome and evaluated their impact on clinical outcome in the follow-up of pyogenic spinal infection in children. In this study, 17 patients (age 2 months-16 years) underwent 51 follow-up MRI scans done 2 weeks-4.75 years after baseline scan. Follow-up scans done at short-term revealed epidural and/or paraspinal soft tissue changes which co-related with the clinical status and laboratory findings in all patients. However, in some cases progression of bone and disk abnormalities was noted in spite of clinical improvement. Long-term follow-up scans revealed soft tissue, bone and disk changes 1-3 years after initial scan in spite of these children being symptom free. The authors concluded that management should be based on the clinical response and that long-term or serial routine follow-ups are not necessary.

THORACIC IMAGING Lung pathologies have traditionally been evaluated using radiography and CT scan. A few recent studies have explored utility of ultrasound and magnetic resonance imaging (MRI) in lung pathologies. Bober and Swietliñski12 investigated the possible role of chest ultrasound in the diagnosis of the respiratory distress syndrome in newborn. Using transabdominal approach, they performed ultrasound examination in 131 consecutive newborns (admitted to the neonatal intensive care unit) in their first day of life with symptoms of respiratory failure. Retrohepatic or retrosplenic hyperechogenicity was shown in 109/131 newborns examined and the diagnosis of respiratory distress syndrome was confirmed by radiography in 101 cases. Respiratory distress syndrome was diagnosed in any patient without retrohepatic or retrosplenic hyperechogenicity. In eight patients with positive ultrasound images unconfirmed by chest X-ray (i.e. false positive sonographic examination), congenital pneumonia was diagnosed in four cases and pneumothorax in one case while in three cases no pathology was found. The authors reported 100% sensitivity and 92% specificity of ultrasound in diagnosis of respiratory distress syndrome.

Chapter 2 ™ Recent Advances in Pediatric Radiology

Copetti and Cattarossi13 evaluated sonographic appearance of transient tachypnea of newborn and its clinical relevance. They performed sonographic examination of 32 neonates with clinical suspicion of transient tachypnea of newborn (TTN) and compared the findings with 60 normal infants, 29 with respiratory distress syndrome, 6 with pneumonia and 5 each with pulmonary hemorrhage and atelectasis. They noted that in TTN the echogenecity of upper lung fields was different from lower lung fields. Specifically, the lower lung fields showed very compact comet tail artefacts while these were rare in superior lung fields. The authors labeled this as “double lung point” which had 100% sensitivity and specificity for diagnosis of TTN. In another study, Copetti and colleagues14 attempted to define the sonographic appearance of neonatal respiratory distress syndrome and evaluate its clinical relevance. They enrolled 40 neonates with respiratory distress syndrome and performed transthoracic ultrasound. In all the patients, sonography revealed echographic “white lung”, pleural line abnormalities (small subpleural consolidations, thickening, irregularity and coarse appearance) and an absence of areas with a normal pattern (i.e. spared areas). When presented simultaneously, these signs had 100% sensitivity and specificity for diagnosis of respiratory distress syndrome. Kurian and colleagues15 compared the findngs of sonography and computed tomography in pediatric patients suffering from pneumonia complicated by parapneumonic effusion. In this retrospective study of 19 patients (age range 8 months-17 years), images were evaluated for effusion, loculation, fibrin strands, parenchymal consolidation, necrosis, and abscess. In this study CT of the thorax did not provide any additional clinically useful information that was not available on chest ultrasound. The authors suggested that the imaging workup of complicated pediatric pneumonia be done with chest radiography and chest ultrasound and CT be reserved for cases where the chest ultrasound is technically limited or discrepant with the clinical findings. Montella and colleagues16 compared the efficacy of high-field MRI and high resolution CT (HRCT) in children and adults with non cystic fibrosis chronic lung disease with the aims of assessing whether chest high-field MRI is as effective as chest HRCT in identifying pulmonary abnormalities; and to investigate the relationships between the severity and extent of lung disease, and functional data in patients with non-CF chronic lung disease. There were 30 children and 11 adults in this study (age range 5.9-29.3 years; median age 13.8 years. 14 patients each had primary ciliary dyskinesia and primary immunodeficiency while another 13 had recurrent pneumonia. All the patients underwent pulmonary function tests, chest HRCT (120 kV, dose-modulated mAs) and high-field 3.0-T MRI (HASTE; transversal orientation; repetition time/echo time/flip angle/acquisition time, infinite/92 milliseconds/ 150 degrees/approximately 90 seconds). The images of both HRCT and MRI were scored in consensus by 2 observers using a modified version of the Helbich scoring system. The maximal score was 25. HRCT and high-field MRI total scores were 11 (range: 1-20) and 11 (range: 1-17), respectively. There was good agreement between the 2 techniques for all scores (r > 0.8). HRCT and MRI total

13

scores, and extent of bronchiectasis scores were significantly related to pulmonary function tests (r = -0.4, P < 0.05). The MRI mucus plugging score was also significantly related to pulmonary function tests (r = -0.4, P < 0.05). The authors concluded that highfield 3.0-T MRI of chest appears to be as effective as HRCT in assessing the extent and severity of lung abnormalities in non-CF chronic lung diseases, and it might be a reliable radiation-free option to HRCT. Bannier and colleagues 17 evaluated the sensitivity of hyperpolarized helium (3He) MRI for the detection of peripheral airway obstruction in younger cystic fibrosis (CF) patients showing normal spirometric results and the immediate effects of a single chest physical therapy (CPT) session. The study involved ten children of 8-16 years of age. Spirometry followed by proton and hyperpolarized 3He three-dimensional lung imaging were performed on a 1.5-Tesla MR unit before and after 20 minutes of CPT. The number of ventilation defects per image (VDI) and the ventilated lung fraction (VF) were quantified. Despite spirometery being normal in all the patients, ventilation defects were found in all patients (mean VDI, 5.1 ± 1.9; mean global VF, 78.5% ± 12.3; and mean peripheral VF, 75.5% ± 17.1). This was well above the VDI in healthy subjects (1.6) as reported in literature. After CPT, although disparate changes in the distribution of ventilation defects were observed, the average VDI and VF did not change significantly. Tracheomalacia is characterized by excessive collapsibility of trachea in expiration. Lee and colleagues18 evaluated air trapping in pediatric patients with and without tracheomalacia. In this retrospective study, the study group and comparison group had 15 patients each. Tracheomalacia was diagnosed if the cross sectional luminal area of trachea decreased by ≥ 50% during expiration as seen on CT scan and confirmed by bronchoscopy. The authors graded the severity of air trapping visually on a 5 point score. All the patients with tracheomalacia and 10/15 children without tracheomalacia showed air trapping. The median air trapping score was significantly higher (p = 0.002) in the study group. However, the patterns of air trapping were not significantly different. These findings have potential implications for diagnosis and management of children with tracheomalacia. Chest radiography, catheter angiography and echocardiography have remained the mainstay of evaluation of patients with heart disease. With the recent availability of advanced multidetector scanners, it has now become possible to evaluate congenital heart diseases using CT scan. Cheng and colleagues19 evaluated the clinical value of low-dose prospective ECG-triggered dual source CT angiography (DSCT) in infants and children with complex congenital cardiac diseases. They compared DSCT findings with transthoracic echocardiography (TTE). The study include 35 patients with the age range of 2 months-6 years. They demonstrated high sensitivity (97.3%) and specificity (99.8%) with mean effective dose of 0.38 ± 0.09 mSv. In this study, the subjective mean image quality score was 4.3 ± 0.7 using a five point scale. Another study evaluated20 step-and-shoot DSCT for evaluation of heart coronary artery and other thoracic structures in young children (age 10 years, those having successful reduction at referring hospital and those who did not undergo an enema reduction at the authors’ institute were excluded. 152 patients met the enrollment criteria. The authors did not find any significant difference in the rate of successful reduction for the patients who initially presented to author’s institute (60.5% as compared to those who had failed reduction at a referring hospital 60.7%). They concluded that children referred to a children’s hospital after failed enema reduction at a referring hospital should undergo repeat enema reduction provided there are no other contraindications. In another retrospective study, Pazo and Losek38 evaluated the demographic and clinical characteristics of children with intussusception and failed initial air enema reduction who were managed by delayed repeat enema attempts. They attempted to identify predictors associated with successful reduction. In this study, there were 21 intussusception events in 20 patients which were managed by delayed repeat air enemas. 9/21 repeat enemas were successful. 4 of the patients who had unsuccessful reduction at first repeat enema underwent a second repeat enema with successful reduction in 3 patients. Thus, 12/25 (48%) repeat enemas were successful. The success rate of delayed repeat enemas was found to be greatest when the intussusception was initially reduced to the ileocecal valve. Demographic characteristics, clinical characteristics, or time from initial enema to first repeat enema were not significant determinant of success at repeat enema. Cystic fibrosis frequently involves liver early in evolution. Liver Steatosis is the most common manifestation while focal biliary cirrhosis is the pathognomonic manifestation. Menten and colleagues39 evaluated the role of transient elastography of liver in patients of cystic fibrosis. In this prospective study, the authors evaluated 134 patients of cystic fibrosis of which 75 were children. In addition, 31 children without cystic fibrosis were enrolled as controls. Liver morphology was classified on a scale of 1-5 representing increasingly severe liver disease. Ten measurements were recorded for tissue elastography for each subject and median value was considered the elastic modulus of liver. The authors found elasticity values of controls, pancreatic sufficient cystic fibrosis and pancreatic insufficient cystic fibrosis patients with ultrasound score < 3 to be comparable and significantly lower than compared to cystic fibrosis patients with ultrasound score of ≥3. In addition, male patients with cystic fibrosis had significantly higher median elasticity (4.7 kilopascals) as compared to female patients with cystic fibrosis (3.9 kilopascals). This preliminary study suggests that transient elastography may be an attractive noninvasive technique to assess and follow-up hepatic disease in cystic fibrosis patients.

16

Section 1 ™ General

URORADIOLOGY Intravenous urography and micturating cystourethrography are important radiological investigations in pediatric uroradiology. However, both of these investigations impart ionizing radiation to the children. Magnetic resonance urography (MRU) and voiding ultrasonography are being evaluated as radiation free alternatives. Hydronephrosis is common urological problem in pediatric population which is evaluated using a combination of several modalities. Perez-Brayfield 40 and colleagues conducted a prospective study to compare comparing ultrasound, nuclear scintigraphy and dynamic contrast enhanced magnetic resonance imaging in the evaluation of hydronephrosis. 96 children with mean age of 4 years (range 1 month to 17 years) were enrolled in the study. Patient sedation, an important issue in pediatric MRI, was administered without complications. The split renal function as calculated by nuclear and MRI scans were comparable in 71 cases (r = 0.93) evaluated. In 50/64 (78%) cases, the final diagnosis at MR urography was similar to that on a combination of ultrasound and nuclear scintigraphy. The authors concluded that dynamic contrast enhanced MRI provided equivalent information about renal function but superior information regarding morphology in a single study without ionizing radiation. Akgun41 and colleagues conducted a retrospective study to assess whether diuretic agent administration in MR urography has an effect on renal length and to determine whether the increase in length can be used to assess renal function. The study group consisted of 20 children of age group 10 months to 13 years. All these children had ureteropelvic junction stenosis. All had 99mTcmercaptoacetyltriglycine (MAG-3) and 99mTc-diethylenetriaminepentaacetic acid (DTPA) diuretic renography performed within 1 month of MR urography. The authors reported that the mean renal lengths measured before and after diuretic administration were 79.02 ± 16.84 mm and 85.61 ± 18.49 mm, respectively. This increase in renal length after diuretic administration was found to be statistically significant (p < 0.001; t = 8.082). In addition, a positive co-relation was observed between the increase in renal length after diuretic injection and functional status of kidneys (p < 0.001; r = 0.547). The better functioning kidneys had higher increase in renal length after diuretic administration. Availability of sonographic contrast agents and harmonic imaging has contributed significantly to the sonographic evaluation of vesicoureteric reflux. In a recent study, Papadopoulou42 and colleagues prospectively evaluated sensitivity of harmonic voiding urosonography (VUS HI) using a second-generation contrast agent (sulfur-hexafluoride gas microbubbles, SonoVue, Bracco, Italy) for the diagnosis of vesicoureteral reflux. The study group included 228 children with 463 kidney-ureter units (KUUs). The patients underwent two cycles of VUS HI and two cycles of VCUG at the same session. The findings of two modalities were compared. Vesicoureteric reflux was demonstrated in 161/463 (34.7%) KUUs, 57 by both methods, 90 only by VUS HI, and 14 only by micturating cystourethrogram. There was (77.5%) (k = 0.40) concordance (359/ 463 KUUs) in findings regarding the presence or absence of vesicoureteric reflux. The difference in the detection rate of reflux between the two methods was significant (P < 0.01). Apart from

showing inferior sensitivity, micturating cystourethrography also missed reflux of higher grade (2 grade I, 65 grade II, 19 grade III, 4 grade IV) as compared to VUS HI (8 grade I, 5 grade II, 1 grade III). The authors suggested that VUS HI and a second-generation contrast agent can be used as an alternative radiationfree imaging method for evaluation of vesicoureteric reflux. Another radiation free approach to evaluation of vesicoureteric reflux involves utilization of MR fluoroscopy. Vasanwala and colleagues 43 have attempted to develop an MRI voiding cystography protocol with continuous real time MR fluoroscopy and validate it against micturating cystouretrography. In this study, eight follow-up patients of vesicouretric reflux were evaluated in a specially designed machine capable of performing MRI as well as fluoroscopic voiding cystourethrography. In this study, MRI had sensitivity of 88% when the grade of reflux differed by less than 1 on two modalities. MRI detected reflux in one patient which was not detected by fluoroscopic voiding cystourethrography.

MUSCULOSKELTAL IMAGING Magni-Manzoni and colleagues44 conducted a study to compare clinical evaluation and ultrasound in the assessment of joint synovitis in children with juvenile idiopathic arthritis. 52 joints in 32 children were evaluated by two pediatric rheumatologists for swelling, tenderness/pain on motion, and restricted motion. The same joints were evaluated by an experienced sonographer for synovial hyperplasia, joint effusion, and power Doppler signal. Overall, 1,664 joints were assessed both clinically and sonographically. On clinical examination joint swelling, tenderness and restricted motion were noticed in 98 (5.9%), 59 (3.5%) and 40 (2.4%) of joints respectively. Sonographic evaluation revealed synovial hyperplasia in 125 (7.5%), joint effusion in 153 (9.2%) and power Doppler signal in 53 (3.2%) joints. A total of 104 (6.3%) and 167 (10%) joints had clinical and sonographic evidence of synovitis, respectively. 86 (5.5%) of the clinically “normal” joints had sonographic features of synovitis. 5 patients were classified as having polyarthritis who were classified as having oligoarthritis or no synovitis on clinical evaluation. In this study, sonographic features moderately correlated with clinical measures of joint swelling, but poorly correlated with those of joint tenderness/pain on motion and restricted motion. The authors concluded that subclinical synovitis is common in juvenile idiopathic arthritis which may have important implications for patient classification and may affect the therapeutic strategy in individual patients. Rooney, McAllister and Burns45 prevalence of synovitis and tenosynovitis in children with juvenile idiopathic arthritis who were felt clinically to have active inflammatory disease of the ankle. Forty nine clinically swollen ankle joints in thirty four patients were included in this study. There were 19 patients with polyarticular disease and 13 with oligoarticular disease. One patient had systemic juvenile idiopathic arthritis. The authors found that 71% of ankles had tenosynovitis and 39% had tenosynovitis alone. Only 29% of clinically swollen ankles had tibiotalar joint effusion alone while 33% had both tenosynovitis and tibiotalar joint effusion. There was statistically significant difference between different subgroups for the frequency of occurrence of medial ankle

Chapter 2 ™ Recent Advances in Pediatric Radiology

tenosynovitis (p = 0.048) and lateral ankle tenosynovitis (p = 0.001).

SUMMARY Several good articles have been published in recent years contributing to improved patient care. The current trends stress on the need of keeping the radiation dose to the minimum possible level when investigating the pediatric patients. Readers are encouraged to stay in touch with recent developments. Use of electronic resources is recommended as quick and inexpensive means for maintaining up to date knowledge. REFERENCES 1. www.imagegently.org last accessed on 05.10.2010. 2. Strauss KJ, Kaste SC. The ALARA concept in pediatric interventional and fluoroscopic imaging: Striving to keep radiation doses as low as possible during fluoroscopy of pediatric patients— a white paper executive summary. AJR 2006; 187:818-9. 3. Strauss KJ, Goske MJ, Kaste SC, et al. Ten steps you can take to optimize image quality and lower CT dose for pediatric patients. AJR Am J Roentgenol. 2010; 194:868-73. 4. Sidhu M, Strauss KJ, Connolly B, et al. Radiation safety in pediatric interventional radiology. Tech Vasc Interv Radiol. 2010; 13:15866. 5. Palchak MJ, Holmes JF, Vance CW, et al. A decision rule for identifying children at low risk for brain injuries after blunt head trauma. Ann Emerg Med. 2003; 42:492-506. 6. Barkovich AJ, Miller SP, Bartha A, et al. MR imaging, MR spectroscopy, and diffusion tensor imaging of sequential studies in neonates with encephalopathy. AJNR 2006; 27:533-47. 7. Liauw L, van Wezel-Meijler G, Veen S, van Buchem MA, van der Grond J. Do apparent diffusion coefficient measurements predict outcome in children with neonatal hypoxic-ischemic encephalopathy? AJNR 2009; 30:264-70. 8. Epelman M, Daneman A, Kellenberger CJ, et al. Neonatal encephalopathy: A prospective comparison of head US and MRI. Pediatr Radiol. 2010; 40:1640-50. 9. Tovar-Moll F, Moll J, de Oliveira-Souza R, Bramati I, Andreiuolo PA, Lent R. Neuroplasticity in human callosal dysgenesis: A diffusion tensor imaging study. Cereb Cortex. 2007; 17:531-41. 10. Wu Z, Mittal S, Kish K, Yu Y, Hu J, Haacke EM. Identification of calcification with MRI using susceptibility-weighted imaging: A case study. J Magn Reson Imaging. 2009; 29:177-82. 11. Wang Q, Babyn P, Branson H, Tran D, Davila J, Mueller EL. Utility of MRI in the follow-up of pyogenic spinal infection in children. Pediatr Radiol. 2010; 40:118-30. 12. Bober K, Swietliñski J. Diagnostic utility of ultrasonography for respiratory distress syndrome in neonates. Med Sci Monit. 2006; 12:CR440-6. 13. Copetti R, Cattarossi L. The ‘double lung point’: An ultrasound sign diagnostic of transient tachypnea of the newborn. Neonatology. 2007; 91:203-9. 14. Copetti R, Cattarossi L, Macagno F, Violino M, Furlan R. Lung ultrasound in respiratory distress syndrome: a useful tool for early diagnosis. Neonatology. 2008; 94:52-9. 15. Kurian J, Levin TL, Han BK, Taragin BH, Weinstein S. Comparison of ultrasound and CT in the evaluation of pneumonia complicated by parapneumonic effusion in children. AJR 2009; 193:1648-54.

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16. Montella S, Santamaria F, Salvatore M, et al. Assessment of chest high-field magnetic resonance imaging in children and young adults with non cystic fibrosis chronic lung disease: comparison to highresolution computed tomography and correlation with pulmonary function. Invest Radiol. 2009; 44:532-8. 17. Bannier E, Cieslar K, Mosbah K, et al. Hyperpolarized 3He MR for sensitive imaging of ventilation function and treatment efficiency in young cystic fibrosis patients with normal lung function. Radiology. 2010; 255:225-32. 18. Lee EY, Tracy DA, Bastos M, Casey AM, Zurakowski D, Boiselle PM. Expiratory volumetric MDCT evaluation of air trapping in pediatric patients with and without tracheomalacia. AJR 2010; 194:1210-5. 19. Cheng Z, Wang X, Duan Y, Wu L, Wu D, Chao B, Liu C, Xu Z, Li H, Liang F, Xu J, Chen J. Low-dose prospective ECG-triggering dual-source CT angiography in infants and children with complex congenital heart disease: First experience. Eur Radiol. 2010; 20: 2503-11. 20. Paul JF, Rohnean A, Elfassy E, Sigal-Cinqualbre A. Radiation dose for thoracic and coronary step-and-shoot CT using a 128-slice dualsource machine in infants and small children with congenital heart disease. Pediatr Radiol. 2010 Sep 4. [Epub ahead of print]. 21. Buonomo C. The radiology of necrotizing enterocolitis. Radiol Clin North Am 1999; 37:1187-98. 22. Faingold R, Daneman A, Tomlinson G, et al. Necrotizing enterocolitis: Assessment of bowel viability with color doppler US. Radiology 2005; 235:587-94. 23. Kim WY, Kim WS, Kim IO, et al. Sonographic evaluation of neonates with early-stage necrotizing enterocolitis. Pediatr Radiol 2005; 35:1056-61. 24. Silva CT, Daneman A, Navarro OM, et al. Correlation of sonographic findings and outcome in necrotizing enterocolitis. Pediatr Radiol 2007; 37:274-82. 25. Dilli D, Oguz SS, Ulu HO, Dumanli H, Dilmen U. Sonographic findings in premature infants with necrotising enterocolitis. Arch Dis Child Fetal Neonatal Ed. 2009; 94:F232-3. 26. Bora R, Mukhopadhyay K, Saxena AK, Jain V, Narang A. Prediction of feed intolerance and necrotizing enterocolitis in neonates with absent end diastolic flow in umbilical artery and the correlation of feed intolerance with postnatal superior mesenteric artery flow. J Matern Fetal Neonatal Med. 2009; 22:1092-6. 27. Jonas MM, Perez-Atayde AR. Liver disease in infancy and childhood. In: Schiff ER, Sorell MF, Maddrey WC, editors. Schiff’s diseases of liver. USA. 10th edn. Lippincott Williams and Wilkins 2007; p. 1307, 1331. 28. Nicotra JJ, Kramer SS, Bellah RD, Redd DC. Congenital and acquired biliary disorders in children. Semin Roentgenol 1997; 32: 215-27. 29. Humphrey TM, Stringer MD. Biliary atresia: US diagnosis. Radiology 2007; 244:845-51. 30. Kim WS, Cheon JE, Youn BJ, et al. Hepatic arterial diameter measured with US: Adjunct for US diagnosis of biliary atresia. Radiology 2007; 245:549-55. 31. Lee MS, Kim MJ, Lee MJ, et al. Biliary atresia: Color Doppler US findings in neonates and infants. Radiology. 2009; 252:282-9. 32. de Carvalho E, Ivantes CA, Bezerra JA. Extrahepatic biliary atresia: Current concepts and future directions. J Pediatr 2007;83:105-20. 33. Nwomeh BC, Caniano DA, Hogan M. Definitive exclusion of biliary atresia in infants with cholestatic jaundice: The role of percutaneous cholecysto-cholangiography. Pediatr Surg Int. 2007; 23:845-9.

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34. Anupindi S, Perumpillichira J, Jaramillo D, Zalis ME, Israel EJ. Low-dose CT colonography in children: Initial experience, technical feasibility, and utility. Pediatr Radiol 2005; 35:518-24. 35. Capuñay CM, Carrascosa PM, Bou-Khair A, Castagnino N, Ninomiya I, Carrascosa JM. Low radiation dose multislice CT colonography in children: Experience after 100 studies. Eur J Radiol 2005; 56:398-402. 36. Sugiyama A, Ohashi Y, Gomi A, Moriya K, Sanada Y, Yatsuzuka M et al. Colorectal screening with single scan CT colonography in children. Pediatr Sur Int 2007; 23:987-90. 37. Curtis JL, Gutierrez IM, Kirk SR, Gollin G. Failure of enema reduction for ileocolic intussusception at a referring hospital does not preclude repeat attempts at a children’s hospital. J Pediatr Surg. 2010; 45:1178-81. 38. Pazo A, Hill J, Losek JD. Delayed repeat enema in the management of intussusception. Pediatr Emerg Care. 2010; 26:640-5. 39. Menten R, Leonard A, Clapuyt P, Vincke P, Nicolae AC, Lebecque P. Transient elastography in patients with cystic fibrosis. Pediatr Radiol. 2010; 40:1231-5.

40. Perez-Brayfield MR, Kirsch AJ, Jones RA, Grattan-Smith JD. A prospective study comparing ultrasound, nuclear scintigraphy and dynamic contrast enhanced magnetic resonance imaging in the evaluation of hydronephrosis. J Urol. 2003; 170:1330-4. 41. Akgun V, Kocaoglu M, Ilgan S, Dayanc M, Gok F, Bulakbasi N. Diuretic-induced renal length changes in the estimation of renal function with MR urography. AJR 2010; 194:W218-20. 42. Papadopoulou F, Anthopoulou A, Siomou E, Efremidis S, Tsamboulas C, Darge K. Harmonic voiding urosonography with a second-generation contrast agent for the diagnosis of vesicoureteral reflux. Pediatr Radiol. 2009; 39:239-44. 43. Vasanawala SS, Kennedy WA, Ganguly A, et al. MR voiding cystography for evaluation of vesicoureteral reflux. AJR 2009; 192:W206-11 44. Magni-Manzoni S, Epis O, Ravelli A, et al. Comparison of clinical versus ultrasound-determined synovitis in juvenile idiopathic arthritis. Arthritis Rheum. 2009; 61:1497-504. 45. Rooney ME, McAllister C, Burns JF. Ankle disease in juvenile idiopathic arthritis: Ultrasound findings in clinically swollen ankles. J Rheumatol. 2009; 36:1725-9.

chapter 3

Interventions in Children PART A—Vascular Interventions Gurpreet Singh Gulati, Sanjiv Sharma INTRODUCTION Interventional procedures in the pediatric age group have a long history. Probably the first intervention performed in a pediatric patient was the reduction of intussusception. The earliest cardiovascular intervention in children performed with angiographic guidance was balloon atrial septostomy. Over the years, although vascular interventional techniques as applied to the adult population have undergone dramatic and continuous innovation, their application to pediatric patients has been delayed, due to a conservative attitude of pediatric medicine practitioners, lack of adequately trained physicians and staff in this subspecialty, and need for special equipment appropriate for pediatric use. Children are not merely “little adults”, nor are the diseases to which they are particularly susceptible, variants of diseases in adult life. Excessive crying, unwillingness for examination, and their inability to describe complaints make a child the most difficult patient. However, it is a challenge to the pediatric interventionist to master the art of ‘talking’ and achieve a successful examination. A friendly environment, affectionate attitude of the medical staff, and a carefully and rapidly performed study, go a long way in conducting a successful procedure. Special Considerations for the Pediatric Patient A discussion between the interventional radiologist and referring physician ensures that the appropriate procedure is performed, the risks for the particular patient are appreciated, and the likely benefit to accrue to the patient is understood. It is particularly imperative to pay special attention to the following details while conducting a pediatric angiography or intervention. These are: 1. Choice of sedation or anesthesia 2. Maintenance of temperature control 3. Fluid balance 4. Radiation safety 5. Equipment selection A dedicated team consisting of the operating radiologist, the radiation and hemodynamic technologists, and the nursing attendant are needed to prepare the catheterization laboratory, prepare and handle the patient, and assist during the procedure. A high-resolution digital angiography system is required to obtain

reliable diagnostic images quickly and to monitor the interventional procedure.

Patient Preparation History and Physical Examination A detailed discussion on the patient’s history taking and examination relevant to general as well as specific angiographic interventional procedures is outside the scope of this chapter. Table 3.1 lists the several components that need to be assessed while evaluating the patient. Informed Consent The parent or guardian of a minor child, and when possible, the patient himself, should understand the reasons for undergoing the procedure, the risks and benefits, the consequences of refusing the procedure, and the alternative therapies available. He or she should then give consent for the procedure. Coagulation Whenever there is a bleeding diathesis, risk of hemorrhage, or a plan to perform systemic thrombolysis, coagulation studies are obtained. Blood is sent for grouping and cross-matching whenever there is ongoing or expected blood loss. Heparin is Table 3.1: Pre-procedure clinical evaluation of the patient 1. 2. 3.

History of the current problem Pertinent medical and surgical history Review of the organ systems • •

Cardiac Pulmonary

• •

Renal Hepatic

4.

• Hematologic (e.g. coagulopathy, hyper-coagulable state) • Endocrine (diabetes) History of allergies

5. 6.

Current medications Directed physical examination

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Section 1 ™ General

administered for arterial catheterization procedures in a dose of 50 units/kg for diagnostic and 100 units/kg for revascularization procedures.

Anesthesia Most diagnostic studies are carried out with intravenous sedation. Difficult interventions such as device implantation or particularly painful procedures are conducted under general anesthesia. In most children, conscious sedation is used, in which the child is conscious, drowsy, and may even close his eyes, but is responsive to verbal commands and able to protect his reflexes and airway. Midazolam is a commonly used, short-acting benzodiazepine that is metabolised by the liver. Its dose is 0.2-1 mg/KBW I.V. The onset of action is 3-5 minutes and the duration of action is 60 minutes. The major side effects are respiratory depression and apnea. A combination of 3 drugs namely, demerol (50 mg), promethazine (12.5 mg) and triclofos (12.5 mg), known as DPT, is the other agent used for conscious sedation. A mixture of the 3 is made into a 2 ml solution, to be given in a dose of 0.06–0.1 ml/KBW I.M. For deeper sedation, a combination of diazepam (0.1 mg/KBW) and morphine (0.1 mg/KBW) may be given I.V. Respiratory depression may occur with higher doses. Patient Immobilization Smaller children are immobilized on a restraining board. Older children will have hand and leg restraints but, if uncooperative, will need to be anesthetized. Temperature Control Neonates and especially premature babies may become hypothermic if a warm operating environment is not maintained. The room temperature should be increased, radiation heaters are required, and the child should be covered quickly while preparing the groin and draping. Diet and Medications Small children need not be kept fasting for more than 3-4 hours prior to the procedure. Routine antibiotics are not prescribed except for high-risk procedures, e.g. splenic embolization. Dose of Radiation and Fluids Isky Gordon et al1 calculated and published the ratio of radiation dose to the skin (in rads) for various procedures as follows: Age (years) Angiography – 20 films Fluoroscopy – 4 minutes

1

5

10

15

1.4 3.2

3.0 4.8

4.8 6.8

7.5 8.8

One must try and minimize the radiation exposure to children who are believed to be more sensitive to the effects of radiation and likely to live for many years with these effects. Digital systems probably do not reduce radiation exposure. However, several precautions may be taken by the operator to reduce the dose. Fluoroscopy at the lowest dose possible (reduce the mAS), pulsed fluoroscopy, removing the scatter grids, and addition of rare earth

filters in the X-ray tubes help to reduce radiation doses to the patient. All fluids and medication must be scaled to the patient size. One may easily administer excessive amounts of fluids and contrast without realizing it. Digital systems (more so with bi-plane angiography systems) help to bring down the volume of contrast material and speeding up procedures. Most infants can tolerate 4 ml/kg of contrast, whereas children over 6 months can tolerate 6 ml/kg, if it is delivered as several injections spread over a period of time. It is important to maintain patient hydration if such large doses are employed.

TECHNIQUES Vascular procedures in pediatric patients require a substantially different approach than that used in the adult population. Many considerations must be taken into account when treating the pediatric population, including the small caliber vessel size, anticipation of spasm, the risk for infection, the propensity for children to rapidly form collateral circulation, the inevitability of growth, and the strong tendency for restenosis and growth arrest to occur. Access Introducer sheaths should be used to preserve vascular access, since multiple catheter/guide wire insertions or exchanges may be needed. Special pediatric access sheaths are available in 4-6 F sizes. These are usually introduced by using a cannula (18-21 G) and an 0.021” guide wire. The angle of entry of the needle should be less perpendicular to the skin, and a small nick in the skin with the blade should be given before introducing the sheath, to prevent pain and a possible vasovagal reaction. Care should be taken to prevent an inadvertent incision in the anterior vessel wall while using the blade. PROCEDURES The major vascular interventional procedures performed in children can be grouped into: A. Embolization B. Angioplasty C. Thrombolysis D. Foreign body removal Embolization Percutaneous transcatheter embolization has replaced surgery for many pediatric vascular problems, and is a treatment alternative in patients where surgery has little to offer. Microcatheter systems, which were initially developed for adult neurovascular interventions, are ideal for pediatric applications. They permit access to small vessels and territories that were previously inaccessible. Hydrophilic coated steerable guidewires permit negotiation of complex vascular loops without provoking spasm or causing dissection. Embolization procedures should only be performed by experienced physicians familiar with the equipment and technical aspects of the procedure. Discussion with the pediatric physicians or surgeons, their support and backup is essential for a safe and successful procedure.

Chapter 3 ™ Interventions in Children

The various pediatric vascular conditions treated by using embolotherapy can be grouped as follows: 1. Vascular anomalies, e.g. arteriovenous malformation (AVM), arteriovenous fistula (AVF), venous malformation (VM), lymphatic malformation (LM), and hemangioma. 2. Hemorrhage from bleeding vessels (due to pseudoaneurysms or vascular involvement in trauma, tumor or inflammation) in various organ systems. 3. Other conditions, e.g. tumors and organ ablation. Goals of embolotherapy include: (i) an adjunctive goal, e.g. preoperative, adjunct to chemotherapy or radiation therapy; (ii) a curative goal, e.g. definitive treatment such as that performed in cases of aneurysms, AVFs, AVMs, and traumatic bleeding; and (iii) a palliative goal, e.g. relieving symptoms, such as of a large AVM, which cannot be cured by using embolotherapy alone.

EMBOLIZATION MATERIALS AND SUBSTANCES Materials used in embolization include coils, ethanol, sodium tetradecyl sulfate, n-butyl cyanoacrylate (NBCA) glue, polyvinyl alcohol (PVA) particles, microspheres, and gelatin sponge (Gelfoam). Vascular Anomalies Vascular anomalies are grouped into 2 categories: hemangiomas and vascular malformations. Vascular malformations are categorised further as high-flow lesions (AVM, AVF), low-flow lesions (capillary malformation, VM, LM), or combined vascular malformations. Embolotherapy with a variety of embolic materials is commonly used in the treatment of vascular anomalies Hemangioma Hemangiomas are benign tumors that require no treatment in most patients. In rare cases, embolization may be necessary (particularly in patients in whom therapy is needed urgently) because of spontaneous hemorrhage or functional abnormality caused by the extreme size of the lesion or the particular anatomic location or because of significant congestive heart failure.2 In addition, embolotherapy is considered useful prior to surgical resection in select patients, and in patients in whom a hemangio-endothelioma causes Kasabach-Merritt phenomenon (platelet trapping).2 Embolotherapy of a hemangioma or hemangioendothelioma can be performed with the use of PVA particles. Coils are infrequently used since they cause more proximal occlusion with potential for recruitment of supply from other arteries and they block future access to the lesion if needed. The goal of embolotherapy is to block a large percentage of the tumoral vessels, thereby preventing further trapping and destruction of the platelets and hastening involution of the lesion. Some tumors may require several sessions of embolotherapy because of revascularization of the tumor or to prevent exceeding the limits of radiation and contrast burden in one session. Infantile hepatic hemangioendotheliomas, a variant of infantile hemangioma, usually are multiple and frequently are complicated by congestive heart failure. In the clinical setting, the goal of embolotherapy is to reduce hepatic arterial flow, which

21

sufficiently relieves high-output cardiac failure. A variety of embolic materials have been used. In some patients, embolization of other nearby arteries (e.g. intercostals) may also be necessary.3 Arterial portography should be performed to exclude the possibility of feeders from the portal system. A rare entity called noninvoluting hemangioma, which is found in the adult population, may also respond to transcatheter embolization (usually with particles such as PVA or microspheres). This procedure is usually performed to improve the cosmetic appearance.

AVM AVMs are typically characterized by a nidus of abnormal vessels in which shunting of arterial blood to veins occurs. These vascular anomalies are usually present during childhood but often demonstrate a sudden increase in size in response to trauma, hormones, or other stimuli. Although a clinical grading system has been used among surgeons, no grading system has been developed for imaging. Most AVMs can be managed by transcatheter embolization and/or sclerotherapy. Some focal AVMs can be treated by surgical excision. Proximal embolization or ligation of the feeding arteries usually worsens matters because of subsequent recruitment of collaterals, and transluminal embolization of the nidus cannot be performed afterwards. The collaterals that develop are more problematic in terms of transcatheter treatment; however, proximal embolization of the feeding arteries may be performed if indicated prior to surgical excision. Whenever possible during primary embolotherapy, the nidus should be embolized.2 Absolute alcohol is the most effective agent in the treatment of AVMs. If the nidus cannot be reached through the feeding arteries, direct percutaneous cannulation of the nidus can be attempted. In selected patients with AVMs, another therapeutic approach is embolic occlusion of the venous outflow. Cervicofacial AVMs For dental arcade AVMs, spontaneous or catastrophic hemorrhage during tooth extraction is a common presentation. Embolization of an AVM in this region requires superselective catheterization of the involved branches of external carotid artery and other regional arterial branches (e.g. thyrocervical trunk) using microcatheters and the coaxial technique.4 Embolotherapy can be performed with NBCA, alcohol, particles, and/or microcoils, depending on the nature and extent of the malformation. Gelfoam can also be used for preoperative embolization. Patients with dental AVMs associated with acute bleeding and loose teeth should undergo embolization immediately prior to tooth extraction. Possible complications of embolotherapy of cervicofacial AVMs include stroke, nerve paralysis, skin necrosis, infection, blindness, and pulmonary embolism. Extremity AVMs In the extremities, AVMs can be diffuse and may involve the entire extremity (Parkes-Weber syndrome). Extremity AVMs typically

22

Section 1 ™ General

Figs 3.1A and B: An arteriovenous malformation of the right arm, with feeders from the profunda brachii artery. Pre (A)- and post (B) – embolization (polyvinyl alcohol particles) angiograms

present with extremity-length discrepancy, high cardiac output, pain, and ulceration. Extremity lesions can be treated with multiple embolizations5 and/or surgical resections or amputation of the extremity (Figs 3.1A and B). A detailed pre-embolization angiographic examination is important for mapping the feeders and draining veins. During the injection of contrast material, the injection rate and duration should be adjusted so that arteriovenous connections can be identified accurately. A high injection rate in a short period is appropriate for AVMs. Selective catheterization with microcatheters is required to reach the nidus of the AVM. Significant complications of embolotherapy possibly include skin necrosis (blisters), nontarget embolization (which also includes pulmonary emboli), and systemic sclerosant toxicity if a liquid agent (e.g., alcohol) is used.

Pulmonary AVMs Pulmonary AVMs are also called pulmonary AVFs. They have a high association with Osler-Weber-Rendu syndrome (also called hereditary hemorrhagic telangiectasia syndrome). Symptoms may include dyspnea, cyanosis, and clubbing. Paradoxical embolization may cause stroke or brain abscess. This anomaly can be classified as simple or complex on the basis of the number of feeders and draining veins. In simple lesions, a single artery and vein are involved; in complex lesions, 2 or more supplying arteries and 1 or more draining veins are involved. Most pulmonary AVMs (80%) are simple. Although a surgical approach (thoracotomy and resection) is the traditional mode of therapy, transcatheter embolization is currently a preferred alternative.6 Transcatheter embolization offers significantly reduced morbidity and mortality rates, particularly in hereditary hemorrhagic telangiectasia syndrome. Embolotherapy for AVMs can be performed with coils, vascular plugs or detachable balloons. Possible complications of

embolotherapy include non-target embolization in the systemic circulation (through the AVM shunt) or in other noninvolved pulmonary arteries. Therefore, properly sizing the coil to the feeding (afferent) artery is essential. A preliminary detailed angiography is essential for mapping the feeders and draining veins, paying particular attention to the size of the feeders. Basically, a successful embolization is accomplished by nesting 1 or more coils in the feeding artery, which occludes flow through the AVM shunt (Figs 3.2A and B). Generally, feeding arteries larger than 3 mm should be embolized. Feeders smaller than 3 mm have low risk of paradoxic embolization and should be left alone unless they are simple and straightforward technically. A coil that is 2 to 3 mm larger than the feeding artery is usually selected. For vascular plug, a 30-50 percent oversizing is recommended. If the feeding artery is large in caliber (>12 mm), a balloon occlusion of the proximal artery via a second groin puncture can be used for a more controlled coil deployment. Postembolization syndrome can occur and is characterized by pleuritic chest pain, pleural fluid, atelectasis, fever, and leukocytosis.

AVF AVFs are relatively large arteriovenous connections and may be congenital or secondary to trauma, surgery, or underlying vascular abnormality (e.g. neurofibromatosis). AVFs may be seen in any part of the body. A patient may present with cardiac failure, localized growth disturbances, neurologic deficits, and ischemic changes. Unlike AVMs, AVFs can be cured with embolotherapy. The embolotherapy technique used depends on the size, location, and hemodynamics of individual lesions. The goal of embolotherapy is to occlude the fistula and the immediate draining vein. Embolization can be achieved by using detachable coils or balloons, or tissue adhesives (glue or onyx). Gelfoam or particles are not appropriate for use in AVF embolization. Detachable coils7

Chapter 3 ™ Interventions in Children

23

Figs 3.2A and B: Right upper lobe pulmonary arteriovenous malformation. Pre (A)- and post (B)-embolization (fibered platinum coils) angiograms. Coils elsewhere are from embolization carried out for other PAVMs in the right lung

or balloons are ideal because these embolic materials can be positioned optimally before they are detached. Balloons also have the advantage of conforming to the size and shape of the abnormal vessels.Microcoils can be dislodged; however, this complication can be minimized by performing flow-control techniques (e.g. balloon occlusion, tourniquet, or blood pressure cuff control). The other disadvantage of coil embolization is that the clot that forms around the coil may dissolve, resulting in recanalization. Appropriate nesting of several coils (packing) can minimize recanalization. Also, thrombosis can be augmented by soaking the coils in thrombin before deployment or by injecting sclerosants around the coils. If adequate coil packing cannot be accomplished, tissue adhesive can be effectively used in combination with coils. Covered stents can also be particularly useful for acquired AVFs (single communications). They have the advantage of maintaining patency of the parent artery. Often, a combined strategy using different techniques is necessary.

VM VMs are the most common type of vascular malformations and can vary significantly in size and clinical presentation. These lesions (usually distinguished by a bluish discoloration with swelling and pain) may also be associated with systemic syndromes such as blue rubber-bleb nevus syndrome or Maffucci syndrome. Sinus pericranii (communication between intracranial and extracranial venous drainage) is also commonly associated with craniofacial VMs. These lesions can be treated with embolotherapy (sclerotherapy) and/or surgical excision.8,9 The type of treatment used depends on the morphology, size, and location of the malformation. A preliminary venogram is usually obtained to evaluate the deep venous system and to determine if any communication exists between the VM and the extremity veins. In particular, a venogram is performed on extremity VMs. The lesion is localized by using ultrasonography, and the largest-appearing cystic portion of the lesion is selected. Then, the lesion is accessed by using real-time

ultrasonographic guidance and a small Angiocath needle (typically, 20-22 gauge). The lesion is studied with contrast agent injections under fluoroscopy as well as digital subtraction angiography. Subsequently, sclerotherapy is performed by using ethanol (absolute alcohol) or sodium tetradecyl sulfate mixed with a contrast medium (Ethiodol or iodinated contrast) under real-time fluoroscopic control (Figs 3.3A and B). Foam sclerotherapy is a technique where a mixture of room air and sclerosant is injected and potentially results in greater agent-malformation contact and lowers volume of sclerosant required. If draining veins are present (as they commonly are), manual compression or a tourniquet should be used to reduce washout of the sclerosant material from the malformation. If large draining veins are present, these veins can be embolized with coils via a percutaneous approach before sclerotherapy. For large head and neck VMs, airway involvement can be a challenging component of the condition in terms of treating the patients. Because alcohol and sodium tetradecyl cause significant edema after sclerotherapy, airway patency should be carefully monitored during and after the sclerotherapy procedure. In patients with large head and neck VMs requiring surgical debulking, presurgical sclerotherapy with NBCA glue can be performed because NBCA causes no significant edema. Two common problems associated with sclerotherapy include skin necrosis (blisters) and/or nerve damage or paralysis. Nerve damage or paralysis can result from the direct toxic effect of the sclerosant agent and/or compression of the nerve by focal compartmental tissue edema (compartment syndrome). In addition, hemoglobulinuria is a relatively common complication; this is treated by aggressive hydration and alkalinization. A less common but more severe complication is cardiac toxicity resulting from the systemic effect of absolute alcohol.

LM LMs can be grouped as microcystic, macrocystic, and mixed. The mixed form of anomaly is probably the most common form of LM.

24

Section 1 ™ General

Figs 3.3A and B: A diffuse venous malformation in the right thigh. Direct puncture venogram showed minimal flow into deep veins (A). Sodium tetradecyl sulphate was slowly injected under fluoroscopic control. Successful occlusion of the malformation was achieved (B)

Lymphatic cysts contain lymphatic fluid. When a single cystic mass (previously termed cystic hygroma when found in the neck) or a conglomerate mass containing a few macrocysts is encountered, surgical excision is considered the most effective treatment. However, some lesions respond really well to sclerotherapy without any complications after 1 or several sclerotherapy sessions. When a mixed form of LM is encountered, the best therapeutic approach may be sclerotherapy for cystic masses, followed by surgical debulking. The microcystic LM, or the microcystic component of the mixed form, does not contain cystic spaces on radiologic studies (including MRI). It demonstrates a characteristic contrast-enhanced pattern of rings and arcs. The sclerosant agents most commonly used are antibiotics (doxycycline), ethanol, sodium tetradecyl sulfate and, most recently, OK-432 (a derivative of group A streptococci). For patients older than 8 years, doxycycline is the most commonly used sclerosant agent. If the patient is younger than 8 years, the options are alcohol, sodium tetradecyl, or OK-432. The amount of alcohol used depends on the patient’s weight, which is a limiting factor in most procedures involving alcohol. The interventional therapeutic approach used for LMs is similar to the sclerotherapy technique used for VMs; however, an initial venogram is usually unnecessary.

Hemorrhage Several types of hemorrhage can be treated with embolization. Examples include hemoptysis; epistaxis; and GI tract, posttraumatic, and iatrogenic hemorrhage (e.g. postbiopsy or nephrostomy tube insertion). GI Hemorrhage Major causes of upper GI tract hemorrhage are ulcer disease, gastritis and varices. The most common causes of a lower GI tract

hemorrhage are vascular malformations and bleeding after endoscopic biopsy. If the bleeding source is identified on arterial angiogram, the patient is treated by using either intra-arterial vasopressin infusion (Pitressin) or embolization of the bleeding mesenteric artery. Embolization is usually the first line of treatment in patients with upper GI tract bleeding and is used as the second line of treatment in patients with lower GI tract bleeding (usually used if vasopressin treatment fails).10 Embolization in the arcades proximal to the bleeding vasa recta is recommended to minimize the risk of bowel necrosis. The most commonly used embolic agents are coils (macrocoils or microcoils) and Gelfoam pieces (torpedoes). Coil embolization is particularly helpful if the bleeding is caused by focal vascular abnormalities such as a false aneurysm. Some interventional radiologists have also used PVA, although the use of PVA or other particles should be avoided because of the risk of bowel infarction. After embolization, control angiography is performed to determine if bleeding (contrast material extra-vasation) continues via any collaterals. The primary advantage of embolotherapy is the immediate cessation of bleeding without need for prolonged catheterization (unlike vasopressin infusion therapy).

Pelvic Hemorrhage Intractable pelvic hemorrhage, usually post-traumatic, should be approached in a similar interventional fashion. A surgical approach to control active bleeding in acute trauma setting is usually not favored. Detailed angiographic examination with superselective injections in the branches of the internal iliac artery is mandatory. Embolization can be performed by using an autologous blood clot, Gelfoam torpedoes, PVA particles, NBCA, coils, or detachable balloons.11 At the capillary level, embolization with small particles or Gelfoam powder is contraindicated (because of the elimination of collateral flow, which results in massive tissue necrosis).

Chapter 3 ™ Interventions in Children

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Figs 3.4A and B: A patient with hemoptysis due to bronchiectasis in the right upper and middle lobe. Selective injection of the hypertrophied right intercosto-bronchial trunk (A) revealed multiple feeders with parenchymal blush. After embolization with PVA particles and gelfoam, the culprit vessel is completely occluded (B)

A specific anatomic relationship between the fracture site and the affected vessel often allows embolization of the branch (frequently the obturator artery) even when no obvious bleeding site is detected.12 In particular, liquid or particle embolization of the inferior gluteal branch of the anterior division should be avoided to minimize the possibility of sciatic nerve injury (this branch supplies muscles of the thigh and buttocks and the sciatic nerve). In addition, embolization of the posterior division of the internal iliac artery should be avoided because of the risk of gluteal necrosis.

Hemoptysis Hemoptysis is considered massive when at least 300 ml of blood is lost in less than 24 hours, and it may be life-threatening. Common causes of massive hemoptysis are cystic fibrosis, bronchiectasis, tuberculosis, and aspergillosis. Malignancy is rarely a cause. Surgical intervention is usually not feasible because of severe pulmonary disease; therefore, embolization of the bleeding bronchial arteries can be life saving.13 Bronchial arteries are variable. They usually arise from the descending thoracic aorta between thoracic vertebre T4 and T7. The right bronchial artery arises from the intercostobronchial trunk in most patients (> 90%). The left bronchial artery usually arises directly from the aorta and is multiple in most patients. Occasionally, the right and left bronchial arteries arise from a common trunk. Although some bronchial branches may supply the spinal cord, the most important of these branches is the artery of Adamkiewicz. This artery usually arises from an intercostal or lumbar artery on the left. Other spinal branches from the right intercostobronchial artery, thyrocervical, or costocervical arteries may be identified. A preliminary thoracic aortogram may be performed, which usually shows abnormal bronchial arteries. An aortogram helps in outlining the bronchial anatomy.

Because of potential source of collaterals, a subclavian arteriogram also is obtained, particularly if the upper lung field is involved. Then, the bronchial arteries are catheterized and studied with selective injections. The most common appearance of the abnormal bronchial artery (the bleeding source) is increased caliber of the bronchial artery with some hypervascularity over the lung field. Contrast agent extravasation, shunting from bronchial to pulmonary arteries, or aneurysmal changes in the involved bronchial artery rarely are identified. Embolotherapy is usually performed with particles (PVA or embospheres) and Gelfoam pledgets (Figs 3.4A and B). When the decision is made to use particles, appropriately sized particles should be used. Sizes are usually 500-710 µm for PVA and 500800 µm for embospheres. Use of coils is inappropriate, and absolute alcohol or cyanoacrylate is no longer used for bronchial artery embolization because of the risk of tissue necrosis (bronchial and/or esophageal). Embolization is performed as selectively as possible (when necessary, by using a microcatheter and coaxial technique) to minimize tissue necrosis and nontarget embolization (e.g. spinal artery). Special care should be taken to prevent reflux by injecting the embolic material slowly under continuous fluoroscopic control. Gelfoam pledgets/torpedoes usually are used to occlude the abnormal artery more proximally after particle embolization.

Epistaxis Intractable epistaxis is a nosebleed that does not respond to conservative treatment (nasal spraying of vasoconstrictors, nasal packing, blood transfusion). Etiologies include uncontrolled hypertension with or without superficial mucosal abnormality (e.g. Osler-Weber-Rendu syndrome). Epistaxis can be treated by either surgical means (e.g. cautery, vascular ligation) or endovascular embolotherapy. Internal carotid

26

Section 1 ™ General

Figs 3.5A and B: A patient with postrenal biopsy hematuria. Selective left renal angiogram (A) shows an arteriovenous fistula from an interlobar artery in the midpole with early filling of the inferior vena cava. Complete occlusion of the branch was achieved with coils (B)

arteriograms are obtained to exclude aneurysms. Then, the external carotid artery is catheterized and control angiography is performed initially to map the vascular anatomy and to check for the presence of a collateral supply to the intracranial circulation. During catheterization of the external carotid artery and its branches, vasospasm is a common problem. Nitroglycerin can be used to treat this. The target branch is usually the pterygopalatine division of the internal maxillary artery, which is distal to the origin of the meningeal and temporal arteries. By using a microcatheter, the pterygopalatine division is catheterized and embolized with particles (most commonly PVA). If bleeding is not caused by a neoplastic entity, embolotherapy can be performed in the 250 to 500 µm range. If a neoplastic entity is the cause, the capillary bed needs to be embolized. This embolization can be accomplished by using smaller particles (150-250 µm). Although the procedure is considered safe if performed by an experienced physician, possible complications can occur. These include ischemia, pain, cranial nerve damage, blindness, and stroke.

Post-traumatic Hemorrhage Post-traumatic hemorrhage can be due to either a blunt or penetrating injury to a vessel, typically arteries in the extremities with penetrating injuries or associated fractures or arteries to the organs (e.g. renal arteries, after blunt trauma). Some patients may present after an orthopedic procedure, such as total hip replacement. An angiographic study is mandatory, not only to aid selecting in the appropriate subsequent embolization procedure but also in planning for possible future surgical interventions. Coil embolization is appropriate in extremity branch arteries responsible for the bleeding because it offers a fast and permanent occlusion of the vessel. The bleeding vessel should be embolized proximal and distal to the site of arterial injury. Avoid embolization

of arteries that endangers limb viability. Hemorrhage or AVF formation after organ biopsy (particularly renal biopsy), or iatrogenic traumatic hemorrhage, is a common complication (i.e. iatrogenic traumatic hemorrhage) that can be treated with embolization (Figs 3.5A and B).

Pseudoaneurysm Pseudoaneurysms occur secondary to trauma or infection and consist of leakage of blood into the confined perivascular space at the site of a vessel wall disruption. Embolization is a good alternative to surgical repair, and is often the treatment of choice, especially when pseudoaneurysms are not accessible or when the patient is not a surgical candidate because of sepsis or other medical conditions.14,15 Embolic materials used for pseudoaneurysms include coils, detachable balloons, thrombin, gelfoam, and NBCA. In large-neck pseudo-aneurysms, a stent placement combined with coil embolization has been described. If the involved vessel cannot be catheterized or if a pseudoaneurysm is close to the skin surface (typically a pseudoaneurysm in the groin after cardiac catheterization), the pseudoaneurysm can be directly punctured with a fine needle (e.g. 22 gauge), and thrombin or NBCA can be injected (Figs 3.6A to D). When the involved artery is embolized with coils, the artery also should be embolized distal to the origin of the pseudoaneurysm so that collaterals do not fill the aneurysm Malignant Tumors Indications for embolotherapy in neoplastic conditions include preoperative embolization and palliative embolization. Embolization helps alleviate symptoms, reduces further dissemination, and increases the response to other treatment modalities (e.g. radiation therapy). Embolotherapy can be used for many types of malignant tumors.16 Renal malignancy is the most common type of tumor treated with embolotherapy. In particular, tumors extending into

Chapter 3 ™ Interventions in Children

27

Figs 3.6A to D: A postcatheterization pseudoaneurysm in the right groin. Selective injections into the right common femoral artery (A) and a branch of the profunda femoris artery (B) shows the jet and the lesion. The lesion was percutaneously punctured and 800 U thrombin was injected (C). Though the pseudoaneurysm occluded immediately (D), it recanalized a few days later and needed surgical repair

the hilum or other adjacent structures for which surgical removal is difficult are treated by using embolotherapy. In these patients, prior embolization of the tumor shrinks the mass and minimizes blood loss during surgical removal. Unresectable tumors can be made operable by means of embolotherapy. If the entity is in its end-stage (disseminated metastatic deposits), the technique can be used for palliation to control pain and hematuria. Other reported malignancies in which embolotherapy has been used include pelvic malignancies and bone tumors. Hemorrhage resulting from malignancy or radiotherapy (e.g. due to radiation cystitis) can be controlled by using embolotherapy.

Chemoembolization Chemoembolization is commonly performed in hepatic malignancies.17 The technique is used in patients with unresectable liver tumors and metastatic liver disease. An essential prerequisite for chemoinfusion/chemoembolization is the presence of a patent portal vein with hepatopetal flow. The bilirubin level should be less than 3 mg/dl to perform chemoinfusion/chemoembolization safely. Vigorous intravenous hydration is required before the procedure for at least 24 hours. Initially, a superior mesenteric arteriogram is usually obtained to demonstrate a variant origin of hepatic artery (accessory or replaced, originating from the superior mesenteric artery) and to demonstrate patency of the portal vein. Then, the celiac trunk and, subsequently, the common hepatic artery are catheterized and studied to outline the vascular anatomy. The involved lobar hepatic artery or, more commonly, the firstor second-order branches of this artery is subsequently catheterized by using a microcatheter and the chemoinfusion material is injected under fluoroscopic guidance. The tip of the catheter must be placed distal to the cystic and gastroduodenal arteries. The most commonly used chemoinfusion mixture consists of 10 ml of iopamidol (Isovue), 20 ml of Ethiodol, and

60 mg of doxorubicin. The chemoinfusion is usually followed by embolization with a slurry of gelatin sponge powder (Gelfoam). Lidocaine is intra-arterially administered to reduce pain after the chemoinfusion/chemoembolization treatment.

Organ Ablation Splenic embolization can be used as a preoperative therapy or as an alternative to surgical removal of the spleen. Indications include post-traumatic bleeding, variceal bleeding secondary to portal hypertension or splenic vein thrombosis, hypersplenism, thalassemia major, thrombocytopenia, idiopathic thrombocytopenic purpura, Gaucher’s disease, and Hodgkin’s disease. Embolotherapy is performed with superselective catheterization/ embolization of the splenic artery by using embolic particles while the tip of the catheter is beyond the caudal pancreatic artery. Careful fluoroscopic control of the splenic area is required to limit the total infarction to approximately 60 percent of the spleen. Renal embolization is an alternative to surgical removal of the kidney, and indications include end-stage renal disease or renovascular hypertension requiring unilateral or bilateral nephrectomy and renal transplant with native kidneys in situ. The procedure requires selective catheterization of the renal artery with further advancement of the catheter so that the catheter is wedged or with the use of a balloon occlusion catheter to minimise the possibility of embolic material spillage into the aorta. The preferred embolic agents are particles (e.g. PVA) and/or liquid agents such as ethanol or NBCA. Postinfarction syndrome is relatively common and characterized by pain, which can be managed with narcotics. This pain usually subsides within 48-72 hours. ANGIOPLASTY The techniques for balloon dilatation of vascular stenosis are the same for children as for adults. Balloon dilatation can be carried out safely even in small children and can permit access to peripheral stenoses. Small balloon catheters (2 mm) and small shaft

28

Section 1 ™ General

Figs 3.7A to C: A 12-year-old female with hypertension: Tight bilateral ostial renal artery stenosis (A) due to aortoarteritis. The right stenosis was treated with balloon angioplasty (B) with a mild residual waist. The lesion opened up well (C) with mild residual disease. The left stenosis was then subjected to angioplasty with a similar result

catheters (3.8 F) can be used with 4 F delivery systems. Small steerable guidewires (e.g. 0.018" or 0.014" PTCA wires) can be used to cross small distal stenosis. For the renal arteries, low profile balloons in diameters of 3-4 mm are employed. Larger balloons up to 20 mm in size are used to treat recurrent coarctation or peripheral pulmonary stenosis. High pressure balloons (up to 17 atm burst pressure) are available with smaller sizes for fibrous stenosis or restenotic lesions. The major indications for angioplasty in children are: 1. Renal artery stenosis (RAS) 2. Aortic stenosis 3. Coarctation of aorta 4. Transplant renal artery stenosis 5. Peripheral pulmonary stenosis 6. Systemic-to-pulmonary artery shunt stenosis 7. Budd-Chiari syndrome due to hepatic vein/IVC stenosis Percutaneous transluminal renal angioplasty (PTRA) is the treatment of choice for RAS. Nonspecific aortoarteritis (NSAA) is responsible for 61% of RAS in our country. Other causes include fibromuscular dysplasia (28%), atherosclerosis (8%), polyarteritis nodosa (2.5%) and renal artery aneurysm of indeterminate etiology (0.5%). NSAA is a chronic and progressive panarteritis of unknown cause that commonly affects the aorta, its major branches and the pulmonary arteries, and results in stenosis, occlusion, dilatation or formation of aneurysms in the involved blood vessels.18,19 Stenosis or obstruction is the most common angiographic abnormality, frequently involving the aorta and the renal arteries, and resulting in systemic hypertension. The complexity of pathological changes in the wall of the aorta and widespread nature of involvement make surgical revascularization a very difficult option. There is also a high prevalence of graft occlusion. Due to these reasons, nonsurgical revascularization techniques have been increasingly used in the treatment of this group of patients.20-22 The goals of therapy in RVH include control of blood pressure (BP) and restoration of renal blood flow. We accept the patients for treatment by nonsurgical revascularization if they have

hypertension uncontrolled by single-drug therapy, angiographic evidence of at least 70 percent stenosis in the renal artery or the aorta with a pressure gradient of more than 20 mm Hg and a normal ESR. Patients with an elevated ESR and/or a positive C-reactive protein test are considered to have an active arteritis and are not generally accepted for this treatment except in certain situations (uncontrolled hypertension, severe ventricular dysfunction, flash pulmonary edema and deteriorating renal function). Anti-hypertensive medication is stopped 24 hr before angioplasty, except for sublingual administration of 5-10 mg nifedipine if the blood pressure is more than 170/110 mm Hg. The patients are treated with aspirin (175-330 mg) daily for 3 days before angioplasty, and this treatment is continued for 6 months after treatment. Heparin (100 IU/kg body weight) is given IV during the procedure and is not reversed afterwards. Blood pressure medication is withheld for 24 hr after the procedure, except for sublingual administration of nifedipine (5-10 mg) if the blood pressure is more than 160/100 mm Hg. If there is severe, uncontrolled hypertension before renal angioplasty, the BP is controlled with nitroprusside drip infusion. For renal angioplasty (Figs 3.7A to C), a pigtail catheter is positioned in the abdominal aorta above the origin of renal arteries for continuous pressure measurement and diagnostic DSA. The diseased renal artery is selectively catheterized through another arterial sheath in the opposite groin and transstenotic pressure gradient is measured. The angiographic catheter is replaced by a commercially available, appropriate sized balloon catheter by using standard exchange technique. The diameter of the involved vessel is measured and a balloon catheter of same size is used for angioplasty. Three to five inflations, for up to 45 sec each, are performed until the balloon “waist” is no longer present or has decreased substantially. We do not use oversized balloon catheters in patients with mild residual stenosis or transstenotic pressure gradients in order to avoid the risk of arterial rupture. Immediately after the procedure, transstenotic pressure is measured and an angiogram is obtained to assess the adequacy of angioplasty.

Chapter 3 ™ Interventions in Children

Alternatively, the procedure can be completed through a single groin approach too. After crossing the stenosis with the angiographic catheter, an 0.014" or 0.018" exchange guidewire is placed in a distal intrarenal branch, and a 6F or 7F (depending upon the patient size) guiding (right coronary or renal double curve configuration) catheter is placed at the ostium of the diseased artery. The appropriately compatible balloon catheters (sometimes, PTCA balloons in monorail configuration may also be used) are then used to dilate the lesion. The advantage of this approach is the avoidance of a second puncture, although the cost of hardware increases. If there is an obstructive dissection or a recurrent ostial stenosis, renal artery stent placement is considered. Pretreatment with ticlopidine (250 mg twice daily) beginning three days before angioplasty is then advisable. This should be continued for atleast six weeks after the procedure. A preshaped renal guiding catheter is positioned at the ostium of the diseased renal artery over an exchange guide wire positioned in a secure distal location in the artery. The selection of the diameter and length of the stent is based on the angiographic morphology of the involved artery. It is advisable to give sublingual nifedipine (5-10 mg) or an intraarterial bolus of trinitroglycerine (100-200 mg) in the renal artery before stent placement. The stent is positioned across the lesion and released by inflating the balloon at the desired inflation pressure for up to 30 sec. Various stent designs are available for use in this location. Balloon-mounted stents are generally preferred for an ostial stenosis. A check angiogram is obtained at the end of the procedure to assess the adequacy of stent release. Intravascular ultrasound is a useful technique to define the endpoint of intervention. Angioplasty or stent placement in the aorta is performed by a similar technique. Angioplasty is considered technically successful if: (i) the aortic or renal artery lumen after angioplasty has less than 30 percent residual stenosis (ii) the arterial lumen is atleast 50 percent larger than its pretreatment diameter, and (iii) the pressure gradient is less than 20 mm Hg and has decreased at least 15 mmHg from the pretreatment gradient. The clinical results of the angioplasty are judged as follows: (i) cure (normal BP after the procedure without antihypertensive drug therapy), (ii) improved (atleast 15 percent reduction in diastolic pressure or a diastolic pressure less than 90 mmHg with the patient taking less antihypertensive medication than before the procedure), and (iii) failed (no change in BP after the procedure).27,28 All patients cured or improved are considered to have benefited from angioplasty. Follow-up is performed by BP and medication evaluation one day, one week, and four to six weeks after treatment and then at six-month intervals. Follow-up angiograms are performed in patients with recurrence of hypertension, in whom contralateral nephrectomy of poorly or nonfunctioning kidney for residual hypertension is planned and in those patients who consent for the procedure. Angioplasty is repeated if restenosis is detected. PTA of the aortic stenosis in NSAA can also be carried out by a similar technique (Figs 3.8A and B). The angiographic features, including eccentricity of the stenosis and presence of

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Figs 3.8A and B: Juxtadiaphgramatic aortic stenosis (due to aortoarteritis) in an 18-year-old girl with resistant hypertension. The stenosis responded well to balloon angioplasty alone with a small dissection flap (B). The systolic pressure gradient across the lesion was significantly reduced and the patient did well on clinical follow-up

diffuse adjacent disease, location of the stenosis in juxtadiaphragmatic segment of the aorta and presence of calcification adversely affect the outcome of PTA, most of whom develop large intimal flaps. Stents have been occasionally used as a “bail-out” measure in salvaging an obstructive dissection in such situations and rarely electively in the treatment of native stenosis. Stents provide an immediate relief of symptomatic obstructive dissection and are also useful in the treatment of recurrent stenosis after successful angioplasty. We do not advocate elective use of stents due to young age of the patients, the cost involved and lack of knowledge about the long-term behavior of stents in the aorta at a growing age. Until recently, it was felt that this diesease is characterized by skip areas of involvement. The findings of recent studies, using crosssectional imaging techniques, suggest that nonspecific aortitis involves a continuous length of the aorta, producing mural and luminal changes in some areas, and only mural changes in the intervening segments. This observation has therapeutic implications. The site of surgical reconstruction or balloon positioning in PTA is based on the demonstration of angiographically normal adjacent segments. The results of cross-sectional imaging suggest that there are extensive wall changes even in angiographically normal areas. The unpredictable outcome of PTA and surgical revascularization in nonspecific aortitis, in our opinion, is caused by the placement of a bypass graft or the balloon catheter within the diseased segments and not from normal to normal aortic segment. In this regard, intravascular ultrasound may be useful in guiding the interventional procedures. Overall, aortic PTA has specific technical problems but has a high technical and clinical success rate. The complication rate is low. Late remodeling occurs in most

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patients and is responsible for delayed clinical benefit despite poor technical success in some patients. Arterial stenosis associated with renal transplantation can often be improved. These obstructions may be at or beyond the suture line. It is important to evaluate the hemodynamic significance of proximal stenosis because in some of these patients extensive peripheral disease due to rejection nullifies the benefit of dilating the proximal lesions. Peripheral pulmonary artery stenosis can sometimes be treated effectively but at moderate risk. Because of the elasticity of pulmonary arteries, these lesions require large balloons for small increases in artery size. Arterial rupture can occur, resulting in death. Because there are no surgical options to treat these lesions, balloon dilatation is the procedure of choice when treatment is clinically indicated. Stenting is a safer and more effective approach to these lesions. After the modified Blalock-Taussig (BT shunt) is placed, stenosis can develop in the subclavian artery, the proximal or distal anastomosis, the graft, or the pulmonary artery. All of these may be treated except the graft stenosis. The best results are obtained in those patients with a traditional BT shunt where the subclavian artery has been directly connected to the pulmonary artery, but this surgery is rarely performed nowadays. Most BT shunts are performed with Goretex grafts, which limit the amount of stretching of the stenosis. Narrowing within the graft is probably caused by kinking, thrombosis, or fibrointimal proliferation.

Complications of Angioplasty Procedures Vascular spasm can occur, particularly in PTRA, and may in turn provoke thrombosis and segmental infarction. 100 Units/kg of heparin is usually given to prevent this, and more may be required for prolonged procedures. Monitoring of heparinisation with measurements of Activated Clotting Time (ACT) should be done. Spasm may be treated with direct intraarterial injection of nitroglycerin (0.25-1.00 µg/kg/min). Thrombosis may occur at the PTA site or at the groin. If it does, then thrombolytic therapy is indicated. Intimal dissection is part of any PTA procedure, and usually does not cause flow obstruction. If an obstructive dissection develops, stents may be used. Vascular rupture is always a concern but can be avoided by appropriate balloon selection. THROMBOLYSIS Experience with thrombolysis in children is limited but has increased because of the need to treat complications of cardiac or peripheral angiography or intervention. Procedures requiring insertion of devices mounted on large shafts are more likely to result in femoral artery thrombosis. The other indications include thrombosis of BT shunts, dialysis fistula, pulmonary artery thrombosis, iliofemoral thrombophlebitis, aortic thrombosis in neonates, and brachial artery occlusion after supracondylar fracture. Contraindications for the procedure include recent surgery or trauma (within the past 6 weeks), any intracranial or gastrointestinal bleed within the past 3 months, renal failure,

gangrene or significant pregangrenous changes in the affected organ system or extremity. Thrombolytic agents include streptokinase, urokinase, or r-tpa. Urokinase is the most commonly employed agent. Local lowdose therapy is unlikely to produce systemic changes in coagulation, whereas systemic therapy may cause undesirable bleeding. The dose of urokinase for local lowdose infusion is 300-500 IU/kg/hr. High dose, short duration treatment given locally often produces clearing of thrombus (Figs 3.9A to D). Treatment failures usually relate to delays in implementing therapy, resulting in maturation of thrombus. The fibrinogen level, thrombin time, prothrombin time, and activated partial thromboplastin time are monitored at regular intervals, and the children are observed in an intensive care unit or neonatal nursery. Complications of intraarterial thrombolysis include systemic bleeding (6 weeks) nutritional supplementation such as patients having neurodisability, craniofacial anomalies, severe gastroesophageal reflux disease etc. This is done under fluoroscopic guidance and initially the stomach is distended with air and punctured by a thin gauge needle. An anchor device is then inserted and pulled to fix the anterior wall of stomach to the abdominal wall.9 Thereafter, again the stomach is punctured and the tract is dilated in order to insert a pigtail catheter. This may be further converted to gastrojejunostomy by passing the guide wire into the jejunum

through the same track and inserting the catheter over it (Fig. 3.13). Care should be taken during the procedure to prevent colonic puncture/injury, which may lead to formation of gastrocolic fistula.

Hepatic Interventions Common hepatic interventions requested in pediatric patients are percutaneous FNA, biopsy and drainage of liver abscess. The technique remains the same for FNA and biopsy as described previously. However, the coagulation profile should be within normal limits for any patient undergoing hepatic intervention, especially biopsy. Also the lesion should be approached via substantial normal liver parenchyma. Percutaneous insertion of the drainage catheter may be required in selected cases of liver abscess.10,11 Depending upon

Chapter 3 ™ Interventions in Children

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Fig. 3.13: Gastro-jejunostomy image with tip of malecots in proximal jejunum

the size and location of the abscess either trochar or Seldinger technique may be used.

Biliary Intervention Percutaneous biliary drainage may be required in children having malignant obstructive jaundice as in patients with metastatic lymph nodes encasing the common bile duct, primary pancreatic tumors or metastatic involvement of pancreas.12 Prior to the procedure, status of biliary confluence (patent/blocked) should be ascertained and accordingly procedure should be performed. In case of a patent primary confluence the catheter may either be placed in the right or the left ductal system. Left sided drainage is generally better tolerated by the children because of less inconvenience caused; and also it is easy to perform under US guidance. In case of a blocked primary confluence the duct which is draining the maximum part of liver should be targeted and at least one third of liver should be drained. Sedation is a must with coagulation profile under normal limits. For patients with a deranged prothrombin time FFP (fresh frozen plasma) may be required. Ideally, the puncture should be performed using a micropuncture set containing a 21G needle and 018’ guidewire which can be further dilated to accommodate 035’ guidewire. After initial puncture performed under US guidance the procedure should be carried under fluoroscopic guidance and efforts should be made to cross the strictured segment and place an internal-external drainage catheter across the stricture reaching upto the duodenum (Fig. 3.14A). However at times, it may not be possible to negotiate the stricture in the first attempt when the system is grossly dilated. In these cases patient may be scheduled for a second session to attempt internalization while the external drain is left in place (Fig. 3.14B). Once the system collapses the internalization of the biliary drainage becomes easier. If internalization fails and the patient is on an external drainage then adequate care should be taken to maintain hydration and electrolyte balance caused by bile loss.

Figs 3.14A and B: (A) Image showing internal external drainage catheter (Ring biliary catheter) placed across the stricture with collapsed biliary system (B) Grossly dilated biliary system with external drainage catheter in situ

Pancreatic Interventions Pancreatic interventions include FNA/biopsy of pancreatic mass and drainage of peripancreatic collections. While attempting pancreatic FNA/biopsy, care should be taken to avoid traversing through spleen, colon and normal pancreatic parenchyma. Pancreatitis is relatively rare in children and is generally seen secondary to trauma. Sometimes, a pseudocyst may form and drainage may be required. While planning drainage the smallest and safest pathway without any intervening abdominal viscera should be chosen for catheter placement, however, if no safe pathway is available transgastric approach may be taken.13 US guidance is preferred for drainage of various abdominal collections, however if proper acoustic window is not available then the drainage should be performed under CT guidance.

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minimal and self limiting. In cases of continuous significant hematuria, patient should be worked up to rule out pseudoaneurysm/arteriovenous fistula, which if present, may need angiographic embolization for treatment.

Percutaneous Nephrostomy (PCN) Common indications for PCN are obstructive renal disease, urinary diversion, for removal of renal stones or placement of antegrade ureteric stent. In cases of obstructive disease or when simply urinary diversion is needed lower polar calyx puncture is preferred. However, if PCN is performed as an initial step for ureteric stenting or percutaneous nephrolithotomy then upper/interpolar calyx should be punctured (Figs 3.15A and B). Intercostal approach may be needed to access the upper pole calyx.15 Commonly, the patient is placed in a prone or semiprone position. The initial puncture of selected calyx (upper or lower) is done under USG guidance. It is preferable to puncture the selected calyx via an oblique posterolateral approach (at 25° from the median plane, with the hub towards patient’s flank) to avoid renal hilar vessels.16 Once the needle tip is inside the calyceal system, urine is seen coming out of the needle as soon as the stylet is removed. At this point, a small amount of diluted contrast may be injected to map the anatomy of pelvicalyceal system and ureter. Further, a floppy tip wire is inserted and directed towards the ureter and using Seldinger technique drainage catheter is positioned in the renal pelvis. The catheter should be properly secured by using various commercially available devices or may be sutured to the skin and dressing should be applied.

Figs 3.15A and B: (A) PCN (Pigtail drainage catheter) through upper pole calyx, as patient planned for PCNL (B) Pigtail catheter replaced with a 12F sheath in upper pole calyx for PCNL

GENITOURINARY INTERVENTIONS Common interventions of genitourinary system include renal biopsies, drainage procedures, percutaneous nephrostomy and ureteric dilatation and stenting. Renal Biopsy Renal biopsy is required for the diagnosis of renal parenchymal disease or renal masses for tissue diagnosis. Being a painful procedure sedation/GA may be needed for a successful biopsy. All renal biopsies are done under US guidance and retroperitoneal approach is preferred especially in cases with renal masses to prevent intraperitoneal seeding. While sampling renal masses a coaxial technique is preferred.14 Sampling of renal capsule should be avoided as it may increase the chances of bleeding/hematoma. Post biopsy hematuria though common is

Ureteric Dilatation and Stenting Common indication of ureteric dilatation and stenting in pediatric patients is post transplant ureteral stricture. Upper pole calyx or interpolar calyx puncture is required for all ureteric interventions (Fig. 3.16A). Dilatation and stenting may be done via a pre-existing PCN catheter or through a new antegrade puncture. Initially, a 0.035’ hydrophilic floppy J tip guide wire is placed in the ureter (Fig. 3.16B). Then an angled 5F angiographic catheter is advanced over it to reach the stricture site and using the combination of guide wire and catheter the stricture is negotiated (Fig. 3.16C). Sometimes, floppy straight tip guide wire may be needed to cross the stricture. After crossing the stricture hydrophilic floppy guide wire is exchanged for a stiff metallic (0.035’ Amplatz extra stiff) guide wire, over which the balloon dilatation of stricture is done. Thereafter, a double J ureteric stent is inserted over the same guide wire using the stent pusher (Fig. 3.16D). The proximal end of the stent may be secured using a suture anchored in one of the side hole so as to position the proximal end of the stent in the renal pelvis while the wire is being withdrawn. A PCN tube should also be placed in the renal pelvis with external end capped for next 24 hours so as to perform antegrade nephrostogram to ensure proper functioning of the stent. Later these stents are removed cystoscopically. CONCLUSION Barring a few, most interventions performed in children are similar to adults; but interventions in children are more challenging due to their small size and uncooperative nature due to the associated pain. It is thus essential to have an experienced team consisting of interventional radiologists, anesthetists and nurses for successful pediatric interventions. Also critical is the availability

Chapter 3 ™ Interventions in Children

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Figs 3.16A to D: (A) Contrast study following interpolar calyx puncture (B) Guide wire was negotiated across the stricture with tip lying within the urinary bladder lumen (C) Further catheter was advanced into the bladder (D) Double J stent was placed over the stiff metallic guide wire

of size appropriate hardware. Concern regarding radiation may be addressed by performing most of the interventions under US guidance, with judicious use of fluoroscopy/CT.

REFERENCES 1. Roebuck DJ. Pediatric interventional radiology. Imaging 2001; 13:302-20. 2. Haaga JR, Nakamoto D, Stellato T, Novak RD, Gavant ML, Silverman SG, Bellmore M. Intracavitary urokinase for enhancement of percutaneous abscess drainage: Phase II trial. AJR Am J Roentgenol 2000; 174(6):1681-5. 3. Beland MD, Gervais DA, Levis DA, Hahn PF, Arellano RS, Mueller PR. Complex abdominal and pelvic abscesses: Efficacy of adjunctive tissue-type plasminogen activator for drainage. Radiology 2008; 247(2):567-73.

4. Pena AH, Cahill AM, Gonzalez L, et al. Botulinum toxin A injection of salivary glands in children with drooling and chronic aspiration. J Vasc Interv Radiol 2009; 20:368-73. 5. Hamza AF, Abdelhay S, Sherif H, et al. Caustic esophageal strictures in children: 30 years’ experience. J Pediatr Surg 2003; 38:828–33. 6. Ko HK, Shin JH, Song HY, et al. Balloon dilation of anastomotic strictures secondary to surgical repair of esophageal atresia in a pediatric population: Long-term results. J Vasc Interv Radiol 2006; 17:1327-33. 7. Gercek A, Ay B, Dogan V, et al. Esophageal balloon dilation in children: Prospective analysis of hemodynamic changes and complications during general anesthesia. J Clin Anesth 2007; 19:286-9. 8. Roebuck DJ, McLaren CA. Gastrointestinal intervention in children. Pediatr Radiol 2010; 29.

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9. Amaral J, Connolly B. Pediatric interventional radiology. In: Geary DF, Schefer F (Eds) Comprehensive pediatric nephrology. Elsevier, Philadelphia 2008; 1053-78. 10. Simeunovic E, Arnold M, Sidler D, et al. Liver abscess in neonates. Pediatr Surg Int 2009; 25:153-6. 11. Lee SH, Tomlinson C, Temple M, et al. Imaging-guided percutaneous needle aspiration or catheter drainage of neonatal liver abscesses: 14-year experience. AJR 2008; 190:616-22. 12. Roebuck DJ, Stanley P. External and internal-external biliary drainage in children with malignant obstructive jaundice. Pediatr Radiol 2000; 30:659-64.

13. Curry L, Sookur P, Low D, et al. Percutaneous cystgastrostomy as a single-step procedure. Cardiovasc Intervent Radiol 2009; 32:28995. 14. Roebuck D, Michalski AJ. Core biopsy of renal tumors in childhood [abstract]. Med Pediatr Oncol 2003; 41:283. 15. El-Nahas AR, Shokeir AA, El-Kenawy MR, et al. Safety and efficacy of supracostal percutaneous nephrolithotomy in pediatric patients. J Urol 2008; 180:676-80. 16. Roebuck D. Pediatric interventional radiology: An overview. In: Spitz L, Coran A (Eds) Operative pediatric surgery. Hodder Arnold, London 2006; 1025-37.

chapter 4

Imaging of Pediatric Trauma Shivanand Gamanagatti, Atin Kumar

Nearly 50% of all deaths in children from 1 to 14 years are the result of trauma.1 The estimates of mortality for children hospitalized after injury are uniformly low because most fatalities occur prior to arrival at a health care facility.1,2 The most common single organ system injury which is associated with highest mortality in pediatric age group is head trauma and nearly 80% of patients with head injuries have associated other organ injuries such as thoracoabdominal injuries. Children are not simple mini adults. Pediatric patients have major anatomic, physiologic, and psychological differences in comparison to adult patients, which play a significant role in the evaluation and management of pediatric trauma patient. List of anatomic differences in adults and children: Implications for pediatric trauma management 3 1. Pediatric body size allows a greater distribution of traumatic injuries, hence multiple injuries are common. 2. Relatively greater body surface area of children contributes to greater heat loss. 3. More anterior position of liver and spleen with less protective musculature and subcutaneous tissue mass, makes them more susceptible to injury. 4. Relatively large size of the kidneys compared to their body size, more mobility and less protection from rib cage makes them very susceptible to deceleration injury. 5. The child’s growth plates are not yet closed, leading to Saltertype fractures with possible limb-length abnormalities following healing. 6. Children have larger head-to-body ratio and thinner cranial bones (< age of 4 years, the calvarium is unilaminar and lacks dipole) due to which injuries to the head are more serious. Imaging differences in children from adults 3-5 Imaging differences in children is based on following aspects: • In children, periosteum is stronger, thicker, highly vascularized, loosely attached to the underlying bone, biologically more active, and often remains intact even in the presence of significant trauma. The bones have more elasticity and plasticity and therefore sometimes may lead to reversible deformities, without manifesting a typical fracture. • Because of increased elasticity of the pediatric bones—we may come across significant organ injuries without any osseous injuries. The child’s cortical bone is also relatively thicker.

•

•

•

•

•

•

•

The growth zone, (consists of transition zone between the elastic metaphysis, with a thinner cortical layer and more spongiosa that is prone to bulge fractures, and the initially purely cartilaginous epiphysis) is the most vulnerable part of the growing bone. In children, the bones and also other injuries heal quicker. Growth potentially corrects axial deviations, hence an anatomically exact repositioning of a fracture may not always be necessary as in adults, and even severe parenchymal injuries may be completely compensated by organ growth. On the other hand, even slight injuries of the growth zone may cause severe growth retardation, osseous deformities and joint problems. Abdominal parenchymal organs are more mobile in childhood, and less protected by the osseous thoracic skeleton. This exposes them to a higher risk of injury. In children, circulation remains stable for very long time but can deteriorate dramatically at any point. Hence, reliable initial assessment as well as effective continuous monitoring and precautionary measures have to be taken to either preventively stabilize the patient or to ensure prompt treatment, particularly important in the era of conservative treatment approach. Children are smaller, have higher breathing and heart rates, and have less fatty tissue or not yet ossified skeletal parts, hence their imaging demands a higher spatial and temporal resolution. Some conditions can be assessed by ultrasound (US) in infants and children that in adults could only be reliably assessed by computed tomography (CT); e.g. injuries of abdominal parenchymal organs, neonatal cerebral hemorrhage. Children are more sensitive to radiation, and have a higher probability to develop radiation-induced cancer. Therefore, utmost radiation protection is compulsory, one should use dedicated imaging algorithms, alternative imaging modality, and radiation reduction imaging protocols (e.g. reduce X-rays, adapt CT protocols). Finally, non-accidental injuries comprise an important aspect of pediatric trauma imaging. It is the duty of any radiologist to pick up potential victims as early as possible to prevent future harm or even life-threatening events.

IMAGING METHODS6 The initial assessment of any child should focus on the following questions:

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Radiographs: Radiographs are the first imaging method used following trauma. Radiographs will be obtained based on the physical examination. For patients sustaining minor trauma, radiographs may not be needed. Plain film radiography is the method most often relied upon in the assessment of suspected non-accidental injury of children. Children younger than 2 years of age with injuries consistent with child abuse will need a skeletal survey including skull, chest, abdomen, and long bone radiographs It is important that good quality radiographs are obtained in all circumstances and that quality should not be compromised just because of the age and lack of cooperation of the child. It is important that all individuals interpreting radiographs in the acute trauma situation should have an understanding of the normal anatomy and basic radiographic projections used. In majority of the cases, X-ray films are taken because of medicolegal considerations rather than clinical necessity.7 Ultrasound: High frequency transducers (7-5 MHz) and ultrasound machines with high spatial and temporal resolution having color Doppler ability are mandatory for a thorough investigation, particularly for imaging neonates and infants. However, in the emergency room just for checking free fluid can be performed using normal equipment using 3-5 MHz transducer. An important use of ultrasound in the acutely traumatized pediatric patient is the ‘Focused Abdominal Sonography for Trauma (FAST)’ exam. When used by a trained radiologist, the FAST evaluation has the potential to provide sensitive and specific identification of intraperitoneal hemorrhage without invasive measures. The FAST examination does not have the ability to reliably detect specific organ injuries.

Potential Uses of the FAST Examination8 • Rapidly identify the source of hypotension in the hemodynamically unstable patient • Assist in decision making in the child with head and abdominal trauma (head and abdominal CT versus laparotomy and/or craniotomy) • Evaluate a stable and alert trauma patient with negative physical examination who otherwise would not routinely undergo radiology imaging • Help prioritize imaging studies in the multiple-trauma patient • Help avoid additional imaging in a child with an already low likelihood of intra-abdominal injury.

CT: CT is still and will remain (at least for the near future) the modality of choice for a quick, reliable and comprehensive assessment of any polytraumatized child. The current generation CT scanners are very fast, have extremely short rotation time, improved Z axis resolution and offer multiplanar reconstruction facilities. Contrast media is essential just as in adults, using weight adapted contrast media dose and age adapted delay. The modern CT scanners have automated radiation dose reduction techniques such as automatic tube current modulation that can substantially reduce patient dose. Currently There are two methods used in the CT systems: z-axis modulation and angular (x- and y-axis) modulation. The aim of this dose reduction or low dose CT strategy is to still achieve a diagnostically reliable image quality at lowest possible radiation dose, by accepting some noise and speckle with consecutive image degradation. In pediatric patients, however, a more critical approach should be adopted with the CT examination being tailored to the specific clinical question being asked, to avoid unnecessary radiation dose.9 The specific indications for chest CT in blunt trauma should be guided by the findings of the initial clinical examination and chest radiograph. • A spinal fracture or fractures of the upper ribs, shoulder girdle, and sternum will often necessitate a contrast-enhanced CT to look for vascular injury • If there is persistent hemorrhagic output from these tubes or progressive pneumomediastinum, to look for bronchial or vascular injury • In the presence of an abnormal mediastinum on plain radiographs, to evaluate for thoracic aortic injury. The most common indications for abdominal CT include lapbelt ecchymosis, gross hematuria, positive FAST scan, all patients with penetrating injury and signs of peritonitis to look for bowel injury. There are three arguments against the routine use of total-body CT in pediatric trauma imaging9 1. An important issue of radiation dose in the pediatric age group 2. Consideration of cost effectiveness in the use of expensive imaging resources 3. There is the risk of the possible demonstration of pseudodisease and clinically unimportant findings by overinterpretation of CT findings Hence, there is a critical need for developing clinical appropriateness criteria for the application of CT in pediatric trauma patients. Given these controversies, the initial imaging evaluation of pediatric trauma should consist of the conventional trauma series (lateral radiograph of the cervical spine, AP radiograph of the pelvis and chest radiograph), in conjunction with a careful and rapid triage by an experienced clinician after taking the mechanism and force of injury into account. This approach will determine the need for additional imaging with cross-sectional techniques, such as ultrasound and spiral or multidetector-row CT. MRI: MRI is rarely used for the initial assessment of acute severe trauma except in some rare situations, most commonly related to the central nervous system and spinal cord. However, MRI is

Chapter 4 ™ Imaging of Pediatric Trauma

also widely used for assessment of traumatic musculoskeletal changes at multiple body areas, particularly the joints. Diagnostic MRI needs appropriate sequence selection and good quality images. Sequence selection is dependent on the clinical question being asked and the possible pathological processes that may be encountered. Image quality is dependent on the signal to noise ratio, spatial resolution, image contrast and any associated artifacts.10

Abdominal Trauma11-13 The management of pediatric blunt abdominal trauma has become increasingly nonoperative over the past several decades. Blunt trauma accounts for nearly 90% of injuries in children. Although skeletal, thoracic, and central nervous system injuries are often clinically evident but intra-abdominal injuries in children are difficult to detect on physical examination, especially in an unconscious child. Hence, imaging plays an important role in diagnosis and management. Contrast-enhanced CT is the preferred imaging modality in the evaluation of intra-abdominal injury. The radiologist’s job is not simply to recognize injuries but also to actively seek imaging signs that indicate the need for surgery. Imaging signs that indicate need of either surgical or endovascular intervention include presence of pneumoperitoneum, intraperitoneal bladder rupture, grade V renovascular injury and active contrast extravasation.14 Nonoperative management is typical for uncomplicated spleen and liver injuries and is gaining popularity for uncomplicated pancreatic and renal injuries. The injuries detected at CT help in determining the appropriate degree of patient monitoring in the hospital (i.e. intensive care unit versus regular ward), length of hospitalization, and amount of activity restriction after discharge. In children, following blunt abdominal trauma, solid-organ injuries predominate, with the spleen being the most commonly injured organ, followed by the liver and kidney. Spleen and Liver Injury to the liver and spleen occurs in 6 to 9% of pediatric patients after blunt abdominal trauma. Although these injuries occur with nearly equal frequency, mortality is greater in patients with hepatic injuries. Patterns of hepatic and splenic injury includes laceration, fracture, hematoma, and rupture (Figs 4.1 and 4.2A to D). Complications of splenic and liver injury include arterial pseudoaneurysm, active intra-abdominal hemorrhage, delayed hemorrhage, and biloma. Pancreas Pancreatic injuries occur in approximately 1 to 2% of children undergoing CT for blunt abdominal trauma. Bicycle handlebar injuries are the most common mechanism of pancreatic injury in children. Pediatric pancreatic injuries are most often isolated, whereas in adults they commonly accompany other abdominal injuries. Direct signs of pancreatic injury include pancreatic laceration, transection, and comminution (Figs 4.3A to D). Peri-pancreatic fat stranding, hemorrhage, and fluid between the splenic vein and

41

pancreas are useful secondary signs of pancreatic injury. Presence of peri-pancreatic fluid in the absence of other abdominal visceral injury should strongly suggest pancreatic injury. CT is useful in delineating the location of pancreatic injury in relation to superior mesenteric artery and vein, as well as the status of main pancreatic duct. Common complications of pancreatic injury in children include pancreatitis and pseudocyst formation. In contrast to adults, trauma is the most common cause of pancreatitis in children. Nonoperative management is preferred in children with blunt pancreatic trauma in contrast to adult patients who undergo surgery in most cases.

Kidney Injury to kidney occurs in 4 to 14% of children presenting with blunt abdominal trauma. Children are more susceptible to renal injury after trauma than adults due to the relatively increased renal size and mobility, decreased amount of perinephric fat, and decreased chest wall protection. Presence of an underlying abnormality such as a mass, horseshoe kidney, hydronephrosis, or multiple cysts may increase that susceptibility by causing the kidney to become bulky and oversized. Most patients with significant renal injury present with hematuria. In some cases significant renal injuries are present in children with only microscopic hematuria or a normal urinalysis. Majority (64-96%) of renal injuries is mild (grade 1-2) (Figs 4.4A to D). Just as with other solid organ injuries in children, nonoperative management is preferred in the management of renal trauma. Complications of nonoperative management include delayed hemorrhage, renal pseudoaneurysm, delayed hematuria, renal scarring, renal cysts, hypertension, infections, and persistent urinoma. Bowel and Mesentery A specific history of lap-belt or handlebar injury should heighten suspicion for bowel injury. Bowel injury occurs in 1 to 8.5% of children after blunt abdominal trauma. Although bowel perforation is one of the few indications for surgery after abdominal trauma, the diagnosis is difficult to establish at CT. Differentiating perforating from nonperforating bowel injury remains a challenge even for an experienced radiologist. Most common CT findings in children with bowel rupture are free peritoneal fluid and bowel wall enhancement (Figs 4.5A and B). Other CT findings include extraluminal gas, bowel wall thickening, bowel dilation, bowel wall defect, mesenteric stranding, fluid at the mesenteric root, focal hematoma, active hemorrhage, and mesenteric pseudoaneurysm. Unexplained peritoneal fluid (free fluid without any solid parenchymal injury, pelvic fracture, or hypoperfusion complex) is another useful indicator of bowel or mesenteric injury. Duodenal injury is rare, occurring in less than 1% of children after blunt abdominal trauma. CT findings that are strongly suggestive of a nonperforating duodenal injury include a thickened

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Fig. 4.1: Axial CT sections of liver showing large contusion involving lateral segment of left lobe of liver with hemoperitoneum

duodenum, mural hematoma, retroperitoneal fluid, and intraperitoneal fluid. Presence of retroperitoneal air has a strong association with duodenal perforation. The distinction is critical, as perforating injuries require surgery, while duodenal hematomas can be managed nonoperatively. Complications of bowel injury include abscess, fistula formation, bowel obstruction, and wound infection. One common mimicker of bowel injury at CT is overhydration, or increased central venous pressure that occurs during aggressive resuscitation. This can lead to bowel wall or mesenteric edema that can obscure or simulate bowel injury.

Chest Trauma Blunt Trauma Chest 9 Thoracic injury is a leading cause of death resulting from trauma in children, second only to head injury. Blunt chest injuries are more common than penetrating injury. Physical evaluation of chest is

limited in children with polytrauma either because of loss of consciousness due to head injury, or because of lack of cooperation; imaging plays an important role in diagnosis. The supine anteroposterior (AP) chest radiograph performed in emergency room may be limited because of technical factors and artifact from overlying immobilization hardware; however, it remains an important tool for the prompt diagnosis of lifethreatening conditions such as a tension pneumothorax. Focused sonography of the lower chest and pericardial space may be very helpful in identifying presence of significant hemothorax or hemopericardium, which may require urgent drainage. Once a severely injured child is stabilized hemodynamically, further imaging tests need to be undertaken to identify internal injury such as contusion, laceration, pneumothorax, hemothorax, pericardial effusion or any vascular injury. Currently, CT is the imaging modality of choice to evaluate chest injury in multitrauma patients, not only in adults, but increasingly in the pediatric population.

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Figs 4.2A to D: Axial CT (A,B) and coronal (C) and sagittal MPR (D) images of upper abdomen showing large contusion involving more than 50% of splenic parenchyma suggesting Grade 3 lesion with hemoperitoneum

Chest wall injuries; Rib fractures are less common in children than in adults because of the compliance/elasticity of the anterior chest wall in children, hence, major internal injuries can occur without rib fractures. Dislocated rib fractures/ unstable flail chest are rarely seen in smaller children. Fractures of the upper ribs and clavicle are often combined with either vascular or esophagotracheo-bronchial injuries. Lower rib fractures are often combined with lacerations of the upper abdominal organs. The fractures of the upper ribs, clavicles, sternum, scapulae, and vertebral bodies or processes are all better assessed with CT than with plain films. Fracture of the trachea or of a bronchus gives following radiological findings: • Misplaced endotracheal tube, but a deformed bronchial contour can also be helpful in the diagnosis. • In the most advanced cases fallen lung sign with collapse of the lung not to the hilum but towards the diaphragm can be seen.

Pleura Pneumothorax can result from penetrating injury to the chest wall, from air leak into the pleural space from an injured lung (laceration),

or in association with central air leak from the tracheobronchial tree (pneumomediastinum). Diagnosis of pneumothorax is straightforward on upright chest radiographs, with demonstration of the visceral pleural line outlined by free pleural air in the apex of the chest. Expiratory films may enhance the visibility of pneumothoraces. In the multitrauma situation, patient is typically in the supine position hence pneumothorax is more difficult to detect and often can be diagnosed only by indirect signs such as deep sulcus sign and double diaphragm sign. CT is more sensitive than chest radiography for small pneumothoraces (Fig. 4.6A), but it is of no clinical significance unless the patient is receiving positive-pressure ventilation support. Presence of a tension pneumothorax (Fig. 4.6B), as evidenced by midline shift on chest radiograph, requires urgent chest tube insertion and therefore this information should be communicated to the treatment team. Hemothorax: Hemothorax is a result of venous or arterial bleeding into the pleural cavity. On supine chest radiography, pleural effusions manifest as a veil-like increased density over the involved hemithorax with

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Figs 4.3A to D: Axial CT and TRUE FISP MR images showing linear complete laceration involving tail of pancreas with peripancreatic minimal free fluid collection (A, B). Axial CT and T2W-FS image showing complete laceration with fluid collection in the region of head of pancreas (C,D)

preserved visibility of pulmonary vascular markings and, in the case of larger amounts of fluid, thickening of the lateral pleural line. CT is more sensitive than radiography for demonstrating small effusions, and Hounsfield density measurements may help confirm their hemorrhagic nature (Figs 4.7A and B). CT is also superior for accurate assessment of chest tube placement and related complications. Pulmonary parenchyma: The radiological findings in pulmonary contusion can vary considerably from patient to patient. There is no air bronchogram but the pattern and extent varies. There are many different radiological appearances. They can be patchy or extensive and confluent, they can be solitary or multifocal, and they can be unilateral or bilateral. Simultaneous aspiration can sometimes confuse the radiological assessment and complicate the outcome. Lung laceration initially may be indistinguishable from the surrounding contusion (Figs 4.8A to D). Because of the disruption of lung tissue, one or more air cavities develop over time and may contain a central density or fluid level because of intrapulmonary hematoma. In the case of large lacerations involving the pleural surface, a bronchopleural fistula may develop. Cavitation of contusions or hematomas, sometimes with air-blood levels on upright chest films or on CT occurs earlier

in time in children than in adults. They can be seen as residual infiltrates for months. Mediastinum: The momentary chest compression and reexpansion of the chest at the time of incident may lead to mediastinal injury and a pneumomediastinum with air tracking and sometimes extending into the neck as subcutaneous emphysema. Pneumomediastinum is recognized by streaky air collections outlining mediastinal structures such as thymus. Another sign of pneumomediastinum is the so called ‘continuous diaphragm sign’ which is due to air beneath the heart. Perforation/rupture of the esophagus may be caused by blunt trauma of chest or by penetrating injury. Unexplained pneumomediastinum and pleural effusions are the most important radiologic signs. If the injury is suspected, an esophagogram should be performed, initially with water-soluble contrast material, followed by dilute barium (Figs 4.9A and B). Detection of a mediastinal hematoma is extremely important, because it may be a clue to an occult traumatic aortic injury (TAI), which is often clinically silent. Mediastinal measurement criteria published in the adult, i.e. mediastinal width greater than 8 cm, mediastinum-to-chest ratio greater than 0.25 have been proven to lack a sufficient predictive value for TAI and do not necessarily

Chapter 4 ™ Imaging of Pediatric Trauma

Figs 4.4A to D: Axial CT (A,B) and Coronal MPR (C) images of upper abdomen showing laceration involving upper pole of right kidney with perinephric hematoma and there is evidence of contrast leakage from the upper pole calyx in delayed scan (D)

Figs 4.5A and B: Axial CT sections (A, B) of mid abdomen showing presence of pneumoperitoneum and abnormal enhancement of walls of small bowel loops with hemoperitoneum suggestive of bowel injury

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Figs 4.6A and B: Axial and coronal MPR images of lungs showing bilateral minimal pneumothorax (A) and tension pneumothorax on right side with collapse of underlying lung (B)

apply to children. Multidetector-row CT angiography has emerged in recent years as a test that is helpful to rule out or demonstrate TAI in patients with an abnormal mediastinum on chest radiography.9 Cardiac injuries are rare but may include both myocardial laceration with ventricular shunting or pericardial hemorrhage (Figs 4.7A and B) and possibly a cardiac tamponade. Chest radiographs can demonstrate enlargement of cardiac silhouette, but they are generally more accurately assessed by CT. Traumatic ruptures of the diaphragm are more common on the left side but are generally very rare.

Penetrating Chest Trauma When they involve the lungs, heart or great vessels they produce similar findings to those that occur with blunt chest trauma. Gunshot wounds are relatively common and the pellet is most often accompanied by a pulmonary consolidation. Even if the pellet has passed through the body a circular tube-like consolidation around the track of the bullet can be seen. Specifically, penetrating pediatric chest trauma tends to produce air within the pleural space, heart, mediastinum or great vessels. Metallic and sometimes other foreign bodies may be seen.

Figs 4.7A and B: Axial CT section of thorax showing right side hemothorax with contusion in bilateral lungs (A) and hemopericardium with minimal right side hemothorax (B)

Musculoskeletal Injuries7,10 Many unique features of the growing skeleton pose specific challenges in imaging skeletal trauma (Vide supra). Differences in the composition and development of the pediatric skeleton (as compared with adults) result in characteristic injuries and fractures. Imaging of these injuries typically begin with plain films, and in the majority no further radiologic evaluation is required. However, Computed tomography (CT) and magnetic resonance imaging (MRI) are used as supplementary imaging studies in pediatric patients with suspected skeletal trauma.

Chapter 4 ™ Imaging of Pediatric Trauma

Figs 4.8A to D: Axial and coronal MIP images (A,B) of lung showing ground glass attenuation lesion in left upper lobe close to the chest wall suggestive of lung contusion. Axial and coronal MIP (C,D) images of lung showing large air filled cavity in left upper lobe with surrounding consolidation suggestive of laceration with surrounding contusion. Note; minimal pneumothorax on left side

Figs 4.9A and B: Axial CT sections of thorax showing pneumomediastinum (A) and contrast leakage from the esophagus (B) given orally suggestive of esophageal rupture

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Figs 4.10A to C: AP radiograph of left knee (A) showing multiple loose bodies overlying the medial condyle of left femur. Axial and sagittal MR (B,C) images showing osteochondral lesions involving both condyles of left femur with multiple loose bodies in relation to medial condyle

Imaging 15 Plain Radiographs In most cases, imaging of pediatric skeletal trauma begins with radiographs, and very few patients require imaging beyond plain films, this is particularly true in cases of common fractures. At least two perpendicular views should be performed. Occasionally, oblique or other views may be needed to diagnose a fracture. CT Scan Multidetector CT (MDCT) with multiplanar and 3-D reconstruction may help in the identification or exclusion of fractures in anatomically complex areas such as the pelvis, spine, elbow and ankle that are not definite on plain radiography. MDCT is also excellent for the evaluation of fracture healing and complications such as pseudoarthrosis formation, post-traumatic physeal closure and growth arrest. MRI With acute pediatric trauma, although plain radiography is still the primary imaging tool, MR imaging has evolved into an essential adjunct diagnostic tool for the prompt identification of occult musculoskeletal injuries. Growth plate injuries and their complications, osteochondritis dissecans (Figs 4.10A to D), avulsion, stress fractures, and soft tissue injuries can be diagnosed early and confidently with MR imaging when other imaging modalities are equivocal. MR imaging, therefore, offers invaluable aid in clinical decisions regarding the timely institution of necessary management to help alleviate symptoms, promote healing, and, more importantly, prevent further complications, such as fractures, degenerative changes, malunion, and growth arrest. MRI is able to accurately evaluate occult and physeal fractures. MRI has been shown to change the classification of physeal fractures significantly, thus

affecting surgical management of these patients. Complications such as physeal growth arrest are also well demonstrated on MRI. In other circumstances it is of limited value, being relatively insensitive in detecting small ossific fragments within a joint and when there is a considerable amount of metallic hardware within the bone. While protocols are important, each examination should be tailored to the individual patient and address the specific area of clinical concern. Drawbacks of MRI include longer imaging times, dependence on patient cooperation, and frequent need for sedation. Musculoskeletal injuries account for 12% of pediatric visits to the emergency department, with fractures making up a large proportion of these numbers. Pediatric bone is more elastic than adult bone and can bend without breaking. This results in unique childhood fractures such as the plastic deformation, torus and greenstick fractures.7,10 Fractures extending into the physeal plate may cause growth arrest, and angular deformity may result. Fractures involving the physis have been classified and described by Salter and Harris.

Types of Pediatric Fractures • Plastic deformation of bone • Torus • Greenstick • Complete diaphyseal fractures – Plastic deformation occurs as a result of longitudinal compression of a long bone. With increasing force, microfractures occur and the bone then loses its capacity to regain its original shape and remains bowed. This fracture occurs most commonly in the radius and ulna. – Torus fractures are also known as buckle fractures and are incomplete fractures occurring on the concave side of the bone with outward buckling of the cortical margin. These

Chapter 4 ™ Imaging of Pediatric Trauma

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fractures occur most commonly in the metaphyseal regions of long bones (Fig. 4.12). – A greenstick fracture is an incomplete fracture occurring only on the convex side of the long bone (Figs 4.11A and B). – A complete fracture occurs when the fracture line propagates completely through the bone and most commonly involve the diaphyseal region.

Physeal Fractures The Salter-Harris classification of physeal fractures is the most widely accepted classification and it relates the radiological appearance of physeal fractures with treatment and morbidity. Salter-Harris Classification I : Transverse through physis. II : Through physis but with a metaphyseal fragment. III : Through physis and epiphysis and therefore intra-articular. IV : Through epiphysis, across physis and through metaphysis (II and III). V : Physeal crush injury (Figs 4.13A to C). A useful rule of thumb is that the higher the grades of injuries, the greater likelihood that the growth plate will be damaged, which can result in long-term complications. Types I, II and III have a relatively good prognosis, whereas type V has a poorer prognosis due to damage to the growth plate. Complications of growth plate injuries include malunion, premature fusion resulting in growth impairment and avascular necrosis.

Figs 4.11A and B: AP (A) and lateral radiographs (B) of right leg showing a greenstick fracture of fibula and oblique fracture of tibia

Head Trauma16 Pediatric head trauma is one of the primary causes of injury, mortality and morbidity in childhood. Imaging supports the diagnosis and treatment of intracranial injuries. The mechanisms of injury in children vary depending on age. The younger the child, the higher the risk of injury, and the risk for asymptomatic intracranial injury is highest for infants younger than 6 months, because of their large heads, weak neck musculature, and relatively thin calvarium. As the child gets older, falls become a less frequent cause of accidental trauma, whereas bicycle injuries and motor vehicle accidents become more common. Broad Classification • Primary lesions: Are the direct result of trauma (Already occurred at the time of presentation) • Secondary lesions: As complications of primary lesions (preventable) – Acute and subacute: Include cerebral edema, ischemia, and brain herniation. – Chronic: Hydrocephalus, the cerebrospinal fluid (CSF) leak, leptomeningeal cyst, and encephalomalacia. According to Location of Lesions • Intra-axial: Cortical contusions, intracerebral hematoma, axonal shearing injuries, gray matter injury, and vascular injury • Extra-axial: Epidural, subdural, subarachnoid, and intraventricular hemorrhage.

Fig. 4.12: AP radiograph of wrist showing torus fracture with outward buckling of the cortical margin of lower end of radius in the metaphyseal region (arrow)

Skull Fractures17 Skull fractures in neonates may be of the following types: linear, diastatic, depressed, compound or buckled. Skull fractures may be diagnosed by CT or plain radiography. Complications from depressed skull fractures include dural tear, cerebral contusion, retained osseous fragments, and cosmetic deformity. Imaging findings of these abnormalities in children are similar to those in adults. However, there are few differences as compared to adults 18 • Skull fractures from minor trauma are more common in children than adults, especially in children younger than 2 years of age.

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Figs 4.13A to C: AP radiograph (A) and coronal STIR MR images (B,C) of right knee showing type V fracture of Salter-Harris classification involving the medial aspect of growth plate

Figs 4.14A and B: Axial CT sections in brain window (A) and bone window (B) showing small biconvex epidural hematoma in parietal region with linear non-depressed fracture of overlying parietal bone

•

The calvarium in a child is softer and thinner than an adult’ and is, therefore, susceptible to fracture. The calvarium is unilaminar without diploe till the age of 4 years. Therefore, skull offers less protection to the child’s brain than it does in the adult, and children with skull fractures are at an increased risk of having intracranial injury.

Extra-axial Injury 1. Epidural hematoma (EDH) (Figs 4.14A and B) 2. Subdural hematoma (SDH) (Figs 4.15A and B) 3. Subarachnoid hemorrhage 4. Intraventricular hemorrhage

Imaging findings of these abnormalities in children are similar to those in adults. However, there are few differences as compared to adults • SDH are more common than EDH • In children, the dura is more firmly adherent to the inner table of the skull and the groove for the middle meningeal artery is shallow, allowing for more mobility of the vessel. For these reasons EDH is less common, and when it does occur, is more often from venous bleeding than arterial. • Skull fractures are less commonly associated with EDH in children because of the increased plasticity of the child’ skull.

Chapter 4 ™ Imaging of Pediatric Trauma

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Figs 4.15A and B: Axial CT sections in bone window (A) and brain window (B) showing small subdural hematoma in left frontal region with linear non-depressed fracture of overlying frontal bone

Fig. 4.16: Axial CT sections of brain showing multiple contusions in left frontal, parietal and right temporal lobes associated with mild perilesional edema. Note; depressed fracture of frontal bone

•

Since the bleeding is often venous, these hematomas evolve slowly, and the clinical presentation of acute EDH in the young child can be less dramatic than in an adult. • Unlike in adults, where the SDH is often unilateral, SDH in children is bilateral in up to 80% of cases. • Often SDH in the pediatric age group is extensive, with involvement of the temporal, frontal and parietal regions. This results from the lack of adhesions in the subdural space that are present in the adult. Intra-axial injuries include contusions (Fig. 4.16), diffuse axonal injury (DAI) (Figs 4.17A to D and 4.18) and intracerebral

hematomas. The imaging appearances of these abnormalities are similar to those in adults. However, skull is relatively smooth in children compared with adults, contusions are less common in the former.

Secondary Head Injury Diffuse cerebral swelling (edema) results from: • Increase in cerebral blood volume (hyperemia), • Vasogenic edema, or • An increase in tissue fluid (cytotoxic edema).

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Figs 4.17A to D: Axial T2W (A), FLAIR (B), DWI (C) and ADC map (D) showing diffuse axonal injury involving the splenium of corpus callosum

Imaging features of cerebral edema include effacement of the cerebral sulci and cisterns, compression of the ventricles and loss of gray-white differentiation. The cerebellum and brainstem are usually spared in cerebral edema and may appear hyperdense (On CT) relative to the affected cerebral hemispheres. Brain herniation occurs secondary to mass effect produced by other causes. There are three types of herniation: 1. Subfalcine 2. Uncal 3. Transtentorial a. Descending b. Ascending All types of herniation are a serious sign of cerebral injury accompanied by displacement of blood vessels and nerves.

Traumatic Ischemia–infarction Infarctions may occur when cerebral swelling leads to transfalcine or transtentorial herniation that compresses the anterior or posterior cerebral arteries respectively. Cerebral ischemia can occur due to regional or global cerebral blood flow changes (Fig. 4.19). Spinal Injuries Spinal injuries in children are rare compared with similar injuries in adults. The prevalence of spinal injuries in children has been reported at less than 10% of all spinal injuries in several studies; however, the mortality rate of craniospinal injury in children is significantly higher than in adults. The cervical spine of young children is fundamentally different from that of adults and the type and outcome of spinal injuries in children also differs from adults.16

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Fig. 4.18: FLASH MR image showing multiple foci of hemorrhages involving gray-white matter junctions and corpus callosum with blooming effect suggestive of diffuse axonal injury

Fig. 4.19: Axial CT sections of brain showing atrophic changes in left cerebral hemisphere with ex-vacuo ventriculomegaly with VP shunt in situ and subdural hygroma, sequelae of post-traumatic brain injury

Anatomic differences in the pediatric cervical spine3 • Relatively larger head size, resulting in greater flexion and extension injuries • Smaller neck muscle mass with ligamentous injuries more common than fractures • Increased flexibility of interspinous ligaments • Infantile bony column can lengthen significantly without rupture • Flatter facet joints with a more horizontal orientation • Incomplete ossification making interpretation of bony alignment difficult • Basilar odontoid synchondrosis fuse at 3 to 7 years of age

• • • • • • •

Apical odontoid epiphysis fuse at 5 to 7 years of age Posterior arch of C1 fuses at 4 years of age Anterior arch fuses at 7 to 10 years of age Epiphyses of spinous process tips may mimic fractures Increased preodontoid space up to 4 to 5 mm (3 mm in an adult) Pseudosubluxation of C2 on C3 seen in 40% of children Prevertebral space size may change because of variations with respiration.

Indications for imaging cervical spine include 19,20 • Midline cervical tenderness • Altered level of alertness

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• •

Figs 4.20A and B: Lateral radiograph of cervical spine (A) and sagittal T2W MR image (B) showing evidence of cord contusion without any obvious visible radiographic abnormality suggestive of SCIWORA

• • • •

Evidence of intoxication Focal neurologic deficits Presence of a painful distracting injury Significant head or facial injury

Indications for thoracolumbar CT 20 • Motor vehicle crash at greater than 35 mph • Falls of greater than 15 feet • Automobile hitting pedestrian with pedestrian thrown more than 10 feet • Assaulted with a depressed level of consciousness

Known cervical injury Rigid spine disease One should be very cautious in using these criteria in children younger than 2 years old, and also in children with congenital or acquired abnormalities (e.g. Down syndrome, juvenile rheumatoid arthritis, prior fracture). When indicated, radiographic evaluation should routinely consist of three views: a cross-table lateral view, an anteroposterior view, and an open-mouth view to help visualize the odontoid process of C1. With these three plain film views of the cervical region, the sensitivity for detecting cervical fractures is 89% and the negative predictive value of these three views adequately done is nearly 100%. CT with multiplanar reformatting has a crucial role in the assessment of cervical spine injury (CSI). MRI is the investigation of choice in the presence of neurological deficit or if there is concern for ligamentous injury as it provides direct evaluation of soft tissue abnormalities such as cord compression/contusion, hematoma, disk herniation and ligament disruption. Types of cervical spine injuries 16 1. Spinal cord injury without radiographic abnormality (SCIWORA), (Figs 4.20A and B) 2. Occiput–C1 injury 3. Atlantoaxial injuries (Figs 4.21A and B) 4. Traumatic spondylolisthesis of C2 (Hangman fracture) 5. Subaxial injuries (C3–C7) 6. Posterior ligamentous injuries 7. Wedge compression fractures 8. Facet dislocations SCIWORA (Spinal Cord Injury Without Radiological Abnormality) is almost unique to the pediatric population and occurs as a consequence of a stretch or distraction injury to the relatively flexible spinal column that exceeds the tensile limits of

Figs 4.21A and B: Sagittal MPR (A) and coronal Thick MIP (B) images showing type1 fracture of dense of C2 vertebra and atlanto-occipital subluxation

Chapter 4 ™ Imaging of Pediatric Trauma

Figs 4.22A and B: Sagittal T1W (A) and T2W MR (B) images showing wedge compression fracture of D12 vertebral body with epidural hematoma. Cord shows normal signal intensity

the spinal cord. Because of increased musculoskeletal elasticity which serves to dissipate the kinetic energy transferred to the child’s body during trauma thus preventing fracture or dislocation is not shared by the spinal cord, which may lead to the occurrence of spinal cord injury without radiological abnormality. There is another hypothesis that SCIWORA results from ischemia due to direct vessel injury or due to hypoperfusion of the spinal cord parenchyma.16 MRI can demonstrate a variety of neural and extraneural findings. The neural findings vary from cord edema, minor or major hemorrhage, to complete cord transection. The extraneural findings are more useful for assessing the stability of the spinal column and include ligamentous disruption, edema or hemorrhage in the paraspinal muscles, disk edema or herniation, or epidural/subdural hematomas.

Thoracic and Lumbar Spine Trauma Approximately 30% of all spinal injury in children occurs in the thoracic region and 17–28% of spinal injury is seen in lumbar vertebrae. The most frequent fracture in the thoracolumbar spine is vertebral body compression fracture (Figs 4.22A and B), almost invariably due to a fall. Anterior wedging is seen on a radiograph. CT is essential to fully demonstrate the fracture extent.16 Normal radiographic parameters and variants: There are several normal anatomical variants that may be encountered during imaging of the pediatric cervical spine 16 1. The atlanto-dens interval (ADI) is defined as the distance between the anterior aspect of the dens and the posterior aspect of the anterior ring of the atlas. This distance should be 5 mm or less in children. An ADI that exceeds 5 mm in lateral flexion and 4 mm in lateral extension indicates instability and is suspicious for ligamentous disruption.

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2. Pseudospread of the atlas on the axis (‘pseudo-Jefferson fracture’) can be seen on anterior open-mouth radiographs. Up to 6 mm of displacement of the lateral masses relative to the dens is common in patients up to 4 years old and may be seen in patients up to 7 years old. 3. Pseudosubluxation: In children, it is seen most commonly at the C2–3 level, but can also be seen at the C3–4 level. This can be differentiated from true subluxation by the posterior cervical line described by Swischuk. The posterior cervical line is drawn along the posterior arches of C1 and C3, and in normal children the posterior arch of C2 lies within 1.5 mm of the posterior cervical line. An abnormal posterior cervical line measurement often indicates the presence of a bilateral pars interarticularis (‘Hangman fracture’) of C2. 4. The absence of lordosis, although potentially pathologic in an adult, can be seen in children up to 16 years of age when the neck is in a neutral position. 5. Posterior interspinous distance: It is a good indicator of ligamentous integrity and should not be more than 1.5 times greater than the interspinous distance one level either above or below the level in question. 6. Vertebral body wedging: In early infancy, cervical vertebral bodies have an oval appearance. These vertebrae take on a more rectangular appearance with advancing age. Anterior wedging of up to 3 mm of the vertebral bodies should not be confused with compression fracture. 7. Retropharyngeal soft tissue buckling: In pediatric patients, widening of the prevertebral soft tissues can be a normal finding that is related to expiration. When lateral radiography of the cervical spine in an infant with possible spinal injury shows wide prevertebral soft tissues, repeat lateral radiography in mild extension and in inspiration should be performed to determine if the apparent soft-tissue abnormality is real.

CONCLUSION Imaging in pediatric trauma must use specific techniques with adapted protocols and algorithms taking the child’s specific conditions into consideration. These differ from standard adult imaging strategies and protocols. REFERENCES 1. Jaffe D. Emergency management of blunt trauma in children. N Engl J Med 1991; 324:1477–82. 2. Minin˜o A, Heron M, Smith B, et al. Deaths: final data for 2004. National vital statistics reports. Hyattsville (MD). National Center for Health Statistics. 3. Marx JA, Holberger RS. Rosen’s emergency medicine: concepts and clinical practice. 5th ed. Mosby 2002; 267–81. 4. Kao SC, Smith WL. Skeletal injuries in the pediatric patient. Radiol Clin North Am 1997; 35:727-46. 5. Resnik CS. Diagnostic imaging of pediatric skeletal trauma. Radiol Clin North Am 1989; 27:1013-22. 6. Kellenberger CJ. Imaging children - what is special? Ther Umsch. 2009 Jan;66(1):55-9. Review. 7. AL Baert, et al. Imaging in Pediatric Skeletal Trauma: Techniques and Applications. 1st ed. Springer 2008; 1-11

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8. Soudack M, Epelman M, Maor R, et al. Experience with Focused Abdominal Sonography for Trauma (FAST) in 313 pediatric patients. Journal of Clinical Ultrasound 2004;32:53–61. 9. Westra SJ, Wallace EC. Imaging evaluation of pediatric chest trauma. Radiol Clin North Am 2005; 43(2):267-81. Review. 10. Sanchez TR, Jadhav SP, Swischuk LE. MR imaging of pediatric trauma. Magn Reson Imaging Clin N Am 2009; 17(3):439-50.Review. 11. Stanescu LA, Gross JA, Bittle M, et al. Imaging of blunt abdominal trauma. Semin Roentgenol 2006;41(3):196–208. 12. Saladino RA, Lund DP. Abdominal trauma. In: Fleisher GR, Ludwig S, Henretig FM,et al.Textbook of pediatric emergency medicine. 5th ed. Philadelphia: Lippincott. Williams & Wilkins 2006; 1339-48. 13. Rose JS. Ultrasound in abdominal trauma. Emerg Med Clin North Am 2004; 22(3):581-89.

14. Bixby SD, Callahan MJ, Taylor GA. Imaging in pediatric blunt abdominal trauma. Semin Roentgenol 2008; 43(1):72-82. 15. Hussain, Barnes. Pediatric Skeletal Trauma—Plain Film to MRI: Imaging Techniques. Applied Radiology 2007; 36(8):24-33. 16. Cakmakci H. Essentials of trauma: Head and spine. Pediatr Radiol 2009; 39 Suppl 3:391-405. 17. Zimmerman RA, Bilaniuk LT. Pediatric head trauma. Neuroimaging Clin N Am 1994; 4:349-366 18. Schutzman SA, Greenes DS. Pediatric minor head trauma. Ann Emerg Med 2001; 37:65-74. 19. Daffner RH. Controversies in cervical spine imaging in trauma patients. Semin Musculoskelet Radiol 2005; 9(2):105-15. 20. Daffner RH, Hackney DB. ACR Appropriateness Criteria on suspected spine trauma. J Am Coll Radiol 2007; 4(11):762-75.

SECTION 2—CHEST

chapter 5

Neonatal Respiratory Distress Akshay Kumar Saxena, Kushaljit Singh Sodhi

A newborn is considered neonate till the age of 28 postnatal days. Respiratory distress constitutes the commonest morbidity requiring admission of a neonate in an intensive care unit. Respiratory distress is defined by presence of at least 2 of the following three features:1 i. Tachypnea (respiratory rate >60 per minute), ii. Retractions (intercostal, subcostal, sternal or suprasternal), iii. Noisy respiration (grunt, stridor or wheeze). Respiratory distress occurs in 11-14 percent of all live births.2 Gestational age has pronounced effect on incidence of neonatal respiratory distress with incidence of respiratory distress on first day of life being higher in babies born at lesser gestation. Kumar and colleagues reported 60 percent incidence of respiratory distress in babies less than 30 weeks of gestational age which reduced to 5 to 6 percent in babies with gestational age more than 34 weeks.2 There are several causes which can give rise to respiratory distress during the neonatal period. They can broadly be classified as follows:3 1. Causes affecting respiration at alveolar level: Hyaline membrane disease (HMD), pneumonia, meconium aspiration syndrome, pneumothorax, pulmonary hemorrhage, primary pulmonary hypertension, transient tachypnea of newborn etc. 2. Structural anomalies of the respiratory tract: Congenital lobar emphysema, congenital caustic adenomatoid malformation (CCAM), congenital diaphragmatic hernia, choanal atresia, tracheoesophageal fistula etc. 3. Extrapulmonary causes: Chest wall abnormalities, congenital heart disease, metabolic acidosis etc. The management of neonatal respiratory distress depends upon clinical history, examination, radiology and laboratory data. The radiology of important causes of respiratory distress in neonatal period is discussed below.

MEDICAL CAUSES OF NEONATAL RESPIRATORY DISTRESS Hyaline Membrane Disease (HMD) HMD, also known as Respiratory Distress Syndrome (RDS), constitutes the most common cause of respiratory distress in the premature newborn infant accounting for up to 60 percent incidence in babies born at or before 29 weeks of gestation. 4 It is a manifestation of pulmonary immaturity and results from impaired

surfactant production by Type 2 pneumocytes leading to formation of hyaline membranes within alveoli and terminal airways, hence the name. Oxygen therapy along with surfactant supplementation currently forms the cornerstone of treatment for HMD. Persistent barotraumas and oxygen toxicity in these neonates, due to intensive oxygen and ventilation therapy, can lead to bronchopulmonary dysplasia (BPD).5 The radiological evaluation of HMD has traditionally relied upon chest radiography. The radiographic findings in untreated HMD reflect the generalized acinar collapse that results from surfactant deficiency. Chest radiograph features in these babies demonstrate decreased expansion of lungs, symmetric generalized consolidation of variable severity, effacement of normal pulmonary vessels and air bronchograms (Figs 5.1A and B).6 The commonly seen “reticulogranular” pattern of lung opacities in HMD represents the summation of collapsed alveoli, transudation of fluid into the interstitium from capillary leak and distension by air of innumerable bronchioles that are more compliant than surfactant deficient lung. This radiographic picture reaches maximum severity around 12–24 hrs of life. In severe cases, there may be complete bilateral “whiteout” of lungs due to extensive consolidation.7 The radiographic findings of HMD also depend on the timing of the administration of surfactant. Early on, despite prevention with surfactant, the lungs are hypoaerated and have a reticulogranular pattern due to interstitial fluid and atelectatic alveoli. The administration of surfactant usually produces some clearing (Figs 5.2A and B), which may be symmetrical or asymmetrical; the asymmetry usually disappears in 2-5 days. Since the surfactant is not evenly distributed throughout the lungs, areas of improving lung alternating with areas of unchanged RDS are common finding.8 With positive-pressure ventilation usually given in these infants, the lung opacity decreases, and they appear radiographically improved. However, the positive pressure required to aerate the lungs can disrupt the epithelium, producing interstitial and alveolar edema. It can also cause the dissection of air into the interlobar septae and their lymphatics, producing pulmonary interstitial emphysema (PIE) (Fig. 5.3). Radiographically, PIE appears as tortuous, 1- to 4-mm linear lucencies that are relatively uniform in size and radiate outwards from the pulmonary hilum. The lucencies do not empty on expiration and extend to the periphery of the lungs.9 PIE can be symmetrical, asymmetrical, or localized to one portion of a lung. Peripheral PIE can produce subpleural blebs

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Figs 5.1A and B: (A) Chest X-ray AP view of a preterm neonate with respiratory distress soon after birth reveals low volume lungs with bilateral consolidation with “Whiteout” of lungs suggestive of HMD. (B) In another preterm neonate with respiratory distress soon after birth, consolidation is less extensive

Figs 5.2A and B: (A) Chest X-ray AP view of a preterm neonate with respiratory distress soon after birth reveals low volume lungs with bilateral consolidation with “Whiteout” of lungs suggestive of HMD. (B) 18 hours after surfactant administration, there is asymmetric clearing of upper zones

which can rupture into pleural space to produce pneumothorax or can extend centrally to produce pneumomediastinum or pneumopericardium. Since, portable chest radiography imparts ionizing radiation and involves delay in availability of information to the clinician, alternative strategies in evaluation of HMD are desirable. A few studies have evaluated use of sonography in diagnosis of HMD.10,11 Using the transabdominal approach for visualization of lung bases, these studies reported a typical pattern of increased retrodiaphragmatic hyperechogenicity (Figs 5.4A and B) which has high sensitivity and specificity for diagnosis of HMD. Another study by Copetti and colleagues,12 tried transthoracic approach for evaluation of HMD. They suggested that a combination of white out lung, absence of areas of sparing and pleural line

abnormalities are 100 percent sensitive and specific for diagnosis of respiratory distress syndrome. Sonography has also been used for follow-up of HMD and early prediction of BPD in neonates suffering from HMD.13,14 In these studies, the incomplete clearance of retrodiaphragmatic hyperechogenicity was found to be a good predictor of later development of BPD. Avni and colleagues13 suggested that Day 18 was the earliest day where the persistence of the abnormal retrodiaphragmatic hyperechogenicity was observed in 100 percent of the patients developing BPD at day 28. At that time, 95.2 percent of the patients without abnormal hyperechogenicity showed uncomplicated evolution and no BPD. They concluded that sonography can be a useful diagnostic tool to determine the occurrence of BPD and to predict as early as day 18 the prematures

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Fig. 5.3: Follow-up chest X-ray of a patient of HMD reveals lucent lesions suggestive of PIE

at risk for the disease. In another similar study, Pieper et al14 reported that Day 9 was the earliest day where persistence of abnormal retrodiaphragmatic hyperechogenicity was observed with the highest predictor values for the development of BPD. These preliminary studies suggest that sonography has a role in early identification of neonates who are at risk of developing BPD in future. However, there is some discrepancy regarding the exact postnatal age at which this can be achieved.

Transient Tachypnea of Newborn (TTNB) Whereas HMD is a disease of premature neonates, TTNB affects term babies. In the fetal life, the lungs are distended with fluid. This fluid is cleared from the lungs during the squeeze through the birth canal while additional fluid is removed by pulmonary capillaries and lymphatics. The delay in clearance of pulmonary fluid leads to TTNB which is also known as “Wet Lung Disease”. The risk factors include delivery by cesarean section; precipitous delivery; and very small, hypotonic or sedated babies. The babies present with mild or moderate respiratory distress soon after birth.15 Typically, the disease is self-limiting with resolution of symptoms in 6-24 hours. Uncommonly, the symptoms may last 2-5 days when it becomes necessary to exclude alternative causes of respiratory distress.3 The radiographic features of TTNB include mild overaeration, mild cardiomegaly, small pulmonary effusion and prominent perihilar interstitial markings (Fig. 5.5). TTNB may mimic reticulogranular pattern of HMD but lacks the under aeration seen in HMD. The radiographic features may occasionally look similar to pulmonary edema or meconium aspiration syndrome.15 Copetti and Cattarossi16 have recently evaluated the lung sonographic findings in TTNB and its clinical relevance. They reported that in neonates with TTNB, lung sonography revealed difference in lung echogenicity between the upper and lower lung

Figs 5.4A and B: (A) Chest X- ray AP view of a preterm neonate with respiratory distress soon after birth reveals low volume lungs with bilateral consolidation with “Whiteout” of lungs suggestive of HMD (B) Coronal transabdominal sonography reveals diffuse retrodiaphragmatic hyperechogenicity suggestive of HMD

areas. There were very compact comet-tail artifacts in the inferior lung fields which were rare in the superior lung fields. They designated this finding the “double lung point”. In this study, “double lung point” was not seen in healthy infants, infants with respiratory distress syndrome, atelectasis, pneumothorax, pneumonia, or pulmonary hemorrhage. Thus, the sensitivity and specificity of the “double lung point” was 100 percent for the diagnosis of TTNB. However, a recent report suggests that “double lung point” may be seen in pneumothorax as well.17

Neonatal Pneumonia Pneumonia is an important cause of neonatal respiratory distress in India with all cases of neonatal respiratory distress being treated

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neonatal intensive care unit patients,19,20 and is responsible for a very high mortality in neonatal intensive care unit patients. The majority of cases are of bacterial etiology. Radiographically, pneumonia is characterized by pulmonary opacities (Fig. 5.6). However, similar appearance may be seen in hyaline membrane disease, transient tachypnea of newborn and meconium aspiration syndrome. Presence of pleural effusion is a helpful pointer towards pneumonia. Furthermore, some of these conditions may coexist with pneumonia.15 The patients with positive radiograph who do not grow causative organism from blood culture are considered “probable pneumonia”.21 It is important to note that in some of the patients with pneumonia, chest X-ray may be normal and diagnosis is made on isolation of organism from blood culture.18 Rarely, pneumonia may mimic mass lesion (Figs 5.7A to D).

Fig. 5.5: Transient tachypnea of newborn: Chest X-ray of a term neonate born by cesarean section and respiratory distress soon after birth reveals normal volume lungs with perihilar infiltrate, prominent cardiac silhouette and pleural fluid in minor fissure (arrow)

Fig. 5.6: Chest X-ray AP view of a neonate on ventilator with respiratory distress reveals patchy consolidation in right lung suggestive of pneumonia

as pneumonia at the first referral unit.18 In a recent study which evaluated the causes of respiratory distress in outborn neonates brought to a referral unit, Mathur and colleagues18 reported pneumonia to be the cause of respiratory distress in more than two third of cases. However, this study did not include patients having surgical causes of respiratory distress. The pneumonia may set in due to transplacental spread, lack of asepsis during delivery, aspiration of amniotic fluid or be acquired during hospital stay for other ailments. Ventilator associated pneumonia is the second commonest hospital-acquired infection amongst pediatric and

Meconium Aspiration Syndrome Meconium aspiration is a disease predominantly affecting term and postmature neonates. While, 10-15 percent of neonates pass meconium in utero, it is rare before 37 weeks.21 Fetus manifests normal shallow regular respiratory movements during intrauterine life. Fetal hypoxia stimulates deep gasping respirations. In addition, it also leads to premature passage of meconium in utero. Meconium is sterile but locally irritant. It can cause obstruction of medium and small airways. In addition, it is a good medium for bacterial growth. The severity of meconium aspiration syndrome depends on several factors including consistency of meconium, adequacy of oropharyngeal suction, associated asphyxia, resuscitative measures etc. The radiographic appearance in meconium aspiration is variable (Figs 5.8A and B). Incomplete bronchial obstruction leads to generalized overeration along with patchy areas of atelectasis secondary to complete bronchial obstruction. There may be subsequent development of pneumothorax and pneumomediastinum. The radiographic appearance may be further complicated by pulmonary edema (because of cerebral, myocardial or renal dysfunction secondary to ischemia), pulmonary hemorrhage, respiratory distress syndrome or pneumonia.15 Some of the babies with meconium aspiration may eventually develop persistent pulmonary hypertension of newborn.3 Pneumothorax Pneumothorax, defined as presence of air in the pleural cavity, is an uncommon but significant cause of neonatal respiratory distress.18,22 Timely identification can be life saving. It can occur spontaneously or be secondary to infection, meconium aspiration, ventilation barotraumas (Fig. 5.9) or lung deformity. The incidence of spontaneous pneumothorax is more in premature babies (about 6%) as compared to term babies (1-2%). The radiographic diagnosis of pneumothorax, although of great clinical significance, can be missed on the X-rays as apicolateral accumulation of air is rather uncommon in the supine films. In the supine position, air preferentially accumulates in anteromedial and subpulmonic recesses.23 The position of air collection is also modified by underlying lung disease. Subpulmonic pneumothorax presents as

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Figs 5.7A to D: Pneumonia mimicking mass lesion: (A) Chest X-ray AP view of a 3-week-old male child with fever and respiratory distress reveals mass like opacity in left upper zone. (B) Mediastinal and (C) Lung window of CECT scan confirm mass like consolidation in left upper lobe. (D) Lung window of repeat CECT scan after 4 weeks of antibiotics reveals resolution of opacity

a relatively lucent region in the left or right upper abdominal quadrant. Sometimes, the only radiographic sign of subpulmonic pneumothorax is deep lateral costophrenic angle (deep sulcus sign).24

Surgical Causes of Neonatal Respiratory Distress Several conditions of neonatal chest require surgical procedure for management. Although listed here as causes of neonatal respiratory distress, it is to be remembered that they may present beyond the neonatal period. In addition, even if discovered during neonatal period, they may be managed conservatively initially. Some of these conditions, like diaphragmatic hernia, can be diagnosed antenatally. Conversely, some of these pathologies may

be discovered accidentally in later life and pose dilemma regarding the need for surgery.

Congenital Lobar Emphysema (CLE) Congenital lobar emphysema or congenital lobar hyperinflation is a disease of multifactorial origin characterized by focal abnormality of a large airway. Unfortunately, the exact abnormality of large airway frequently remains a mystery as it is left inside the body of the patient proximal to the ligated bronchial stump. However, potential culprits include bronchomalacia, kinks, webs, mucosal webs and crossing vessels. Whatever the etiology may be, the result is impairment of bronchial function and hyperinflation of a pulmonary lobe.25 Left upper lobe is the commonest site of involvement (40-50%) followed by right middle lobe (28-34%) and

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Fig. 5.9: Neonate on ventilator developed respiratory distress. Chest X-ray AP view revealed gross right pneumothorax

Figs 5.8A and B: (A) Term neonate with meconium aspiration. Chest X-ray AP view reveals bilateral hyperinflation. (B) In another neonate with respiratory distress and suspected meconium aspiration, chest X-ray AP view reveals bilateral pulmonary opacities. Pulmonary opacities in meconium aspiration may be due to atelectasis, chemical pneumonitis or super added pneumonia

right upper lobe (20%).26 The hyperinflated lobe causes mediastinal shift and atelectasis of the adjacent lobes. Prenatal diagnosis is unusual in congenital lobar emphysema. Postnatally, the age of onset of symptoms and degree of respiratory distress may be variable. However, more than 50 percent become symptomatic within first week. Not all the symptomatic patients may require immediate surgery.25,27 The postnatal chest radiograph, if acquired early in life, may reveal overdistended fluid filled lobe. Later on, the radiograph shows characteristic hyperinflation of a lobe with splayed pulmonary vessels, atelectasis of adjacent lobes and contralateral mediastinal shift (Fig. 5.10). The differential diagnosis is pneumothorax wherein the hyperlucent region will be

Fig. 5.10: Chest X-ray AP view of a neonate with respiratory distress reveals emphysematous left upper lobe with contralateral mediastinal shift suggestive of congenital lobar emphysema. Presence of vascular markings differentiate congenital lobar emphysema from pneumothorax

devoid of pulmonary vascular markings. If required, computed tomography scan (CT scan) can be performed to resolve the diagnosis. The findings seen on chest X-ray can all be seen on CT scan. Computed tomography can also reveal treatable extrinsic and intrinsic treatable cause of partial bronchial obstruction.26 Uncommonly, the lobar emphysema may affect two lobes. Either the lobes may be affected simultaneously or the second hyperinflated lobe may be detected after first thoracotomy. The bilobectomy procedure may be performed as one stage or two stage procedure.27

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Figs 5.11A to D: A 3-day-old neonate with respiratory distress. Mediastinal window of contrast enhanced CT scan (A) axial (B) coronal reconstruction and (C) Right parasagittal reconstruction reveal a cystic mass lesion in right upper lobe. (D) Lung window additionally reveals bilateral pneumonia. This lesion can be CCAM or bronchogenic cyst. The patient was managed conservatively and is awaiting surgery

Congenital Cystic Adenomatoid Malformation (CCAM) CCAM (also called CPAM-congenital pulmonary airway malformations) is a hamartomatous lesion believed to occur because of the failure of pulmonary mesenchyme into normal bronchoalveolar tissue.15,26 On the basis of pathological findings, Stocker,28 classified the CCAM into five types. However, radiological classification consists of three types:26 Type I: It constitutes 50 percent of CCAM patients and shows multiple or single large cysts which communicate with the bronchial tree of the affected lobe. Type II: It constitutes 40 percent of CCAM and shows multiple cysts that rarely exceed 1.2 cm in diameter and communicate with the bronchial tree of the affected lobe.

About one-third of these patients have associated congenital anomalies. Type III: It is least common type (10% of patients). It consists of multiple small (2 cm) in the posterior nasopharyx narrowing or obliterating the nasopharyngeal air lucency. CT also demonstrates tonsillar adenoidal enlargements well (Figs 8.4A to C). Enlarged palatine

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tonsils appear as soft tissue mass projecting on the posterior aspect of soft palate.1 On T2W and STIR images adenoids and tonsils appear hyperintense.

Glossoptosis Glossoptosis means abnormal posterior motion of the tongue during sleep and is associated with underlying hypotonia, macroglossia or micrognathia. Macroglossia and micrognathia may be diagnosed on lateral radiograph. However glossoptosis can be demonstrated on dynamic sleep fluoroscopy or cine MRI. Hypopharyngeal Collapse Hypopharyngeal collapse refers to cylindrical collapse of the hypopharynx; with its anterior, posterior and lateral walls all moving centrally. It is associated with disorders of decreased muscular tone. This can be diagnosed on cine fluoroscopy or MRI.

Figs 8.4A to C: Enlarged adenoids and tonsils: CECT of a 9-year-old boy with history of snoring reveals enlarged adenoids (A) and palatine tonsils (B). Sagittal MPR (C) shows narrowing of the nasopharyngeal airway

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Subglottic Obstruction Subglottic Stenosis Short segment subglottic stenosis is often congenital in origin (Figs 8.5A and B). Post-intubation Stenosis Prolonged intubation can lead to either tracheomalacia or airway stenosis, particularly with oversized endotracheal tubes or balloon cuffs. Airway stenosis consequent to prolonged intubation usually occurs at the level of cricoid cartilage, which is the narrowest part of the upper airway7 (Figs 8.6A to C). Subglottic Hemangioma Hemangiomas located in the soft tissues of the neck may extend into the subglottic airway. Large hemangiomas or vascular malformations can cause obstruction at any level (Figs 8.7 and 8.8). These present in infancy, often at less than 6 months of age; and may be associated with hemangiomas of the face or trunk. Plain radiographs reveal asymmetric subglottic narrowing with associated soft tissue. On cross-sectional imaging, the lesions show intense contrast enhancement which may be nodular. These lesions are unilateral or bilateral, but often asymmetric and occasionally circumferential. On T2W images, as elsewhere hemangiomas appear hyperintense.2 Although a benign lesion with a natural history of proliferation and involution, complications of bleeding and airway obstruction can be life threatening. Spontaneous regression is typical. Endoscopy confirms the diagnosis. When the presentation demands active management, as in patients with symptomatic airway compromise, treatment options include systemic or intralesional corticosteroids, laser ablation, interferon therapy or surgical excision.4,8 LOWER AIRWAY OBSTRUCTION Central Airways Small airway diseases such as asthma and bronchiolitis are more common than central causes of obstruction. The central causes may be extrinisic or intrinsic (involving either the wall or lumen). Investigations include frontal and lateral radiographs of the airway and chest. The neck radiographs help to exclude upper airway obstruction. Chest radiographs should be evaluated for tracheal caliber, cardiac size, position of the aortic arch, mediastinal widening, asymmetric lung aeration, lung collapse or consolidation and radiopaque foreign body. The length of tracheal narrowing and involvement of anterior/posterior walls should be noted. If the radiographs are suggestive of an intrinsic cause of obstruction, then one can proceed with fiberoptic bronchoscopy. If the suspected cause is extrinsic then further cross-sectional imaging is indicated. The choice between CT and MRI is not clearly defined. While MRI has the advantage of being radiation free and not dependent on intravenous contrast, its main drawback is the long scanning times. The need for sedation especially in a child with airway compromise often negates the advantages of MRI, making CT the

Figs 8.5A and B: Subglottic stenosis: CECT of a newborn with stridor. Axial (A), sagittal VRT (B) images show a short segment, smooth subglottic stenosis (arrow)

preferred modality. Both modalities offer good contrast between the central airway and surrounding structures, while the lungs are better visualized on CT.

Extrinsic Causes Any mass lesion of the mediastinum such as nodes and cysts include the non-vascular causes of airway compression. Chest wall deformities may similarly result in airway compromise. The classical vascular causes include double aortic arch, anomalous left pulmonary artery (pulmonary sling) and innominate artery compression syndrome. However, several other vascular causes such as dilatation of pulmonary artery (Figs 8.9A to C), enlargement of ascending aorta, midline descending aorta and right arch with aberrant left subclavian artery can also result in airway compression. A vascular ring encircling the airway occurs as a

Chapter 8 ™ Pediatric Airway

Figs 8.6A to C: Post-intubation stenosis: A short segment, smooth subglottic stenosis is seen on sagittal MPR (A), coronal minIP (B) and VB (C) CT images of a child with history of prolonged intubation (For color version Fig. 8.6C see plate 1)

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Figs 8.7A to C: Hemangioma: NCCT (A) and CECT (B, C) image reveal an enhancing, well defined soft tissue mass significantly narrowing the oropharyngeal and subglottic airway

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Fig. 8.8: Lymphangioma: CECT neck of a neonate showing a large multiseptated, multicompartmental cystic lesion obliterating the oropharyngeal airway

result of the failure of primitive vascular structures to fuse and regress normally during the development of the aortic arch, pulmonary arteries, and/or ductus arteriosus. Patients with vascular rings may have wheezing, stridor, feeding difficulties, choking episodes, or even aspiration pneumonia; depending on the degree of tracheal and esophageal narrowing.4 Plain radiographs and barium swallow cannot reliably distinguish among the types of vascular ring. Cross-sectional imaging, either with CT or MR, is helpful in delineating the anatomy and aiding in presurgical planning and postsurgical assessment.4,9,10

Vascular Causes Vascular Rings Double Aortic Arch: Double aortic arch is a congenital arch anomaly, and is the commonest vascular ring to cause airway compression. It is usually an isolated anomaly. Both right and left arches are seen to arise from the ascending aorta and join to form the descending aorta. Right arch is commonly larger and posterosuperior.1,2 The two arches surround and compress the trachea anteriorly, and esophagus posteriorly. The level of compression is mid to lower thirds of intrathoracic trachea.1,2 On radiography, lateral tracheal indentations are seen. On cross-sectional imaging, it is important to determine the dominant arch (side), as the surgical approach differs accordingly. Pulmonary sling: Pulmonary sling refers to a pulmonary artery anomaly wherein the left pulmonary artery arises from the proximal right pulmonary artery, forming a “sling” around the trachea. It subsequently passes between the trachea and esophagus as it courses towards the left lung. It may be associated with congenital

Figs 8.9A to C: Vascular compression : Chest radiograph (A) and CECT (B and C) of a 5-month-old infant with ventricular septal defect, showing enlarged central pulmonary arteries with volume loss of the left lung. There is compression of the bilateral main bronchi by the enlarged pulmonary arteries, especially the left main bronchus (arrow)

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heart disease and complete tracheal rings, worsening the airway compromise.1,2 Frontal radiograph reveals asymmetric lung inflation. On lateral radiograph, there is posterior compression of the trachea with anterior esophageal impression. It is the only vascular ring to course between the trachea and esophagus, to be associated with asymmetric lung inflation and also the only one to cause anterior indentation on the esophagus.1,2 Innominate artery compression syndrome: Innominate artery (Brachiocephalic) crosses the trachea anteriorly, just below the thoracic inlet. In infants, it arises more to the left than adults. In addition the presence of a large thymus in the mediastinum and lack of rigidity of infantile trachea results in tracheal compression. The range of symptoms vary from none to stridor and dyspnea resulting from severe compression. Most children outgrow the disease and surgery is reserved only for those with severe compression. Lateral radiographs reveal focal anterior indentation of the trachea. CT and MRI detail the severity of the compression and exclude other causes.1, 2 Right arch with aberrant left subclavian artery: This is an arch anomaly wherein the aortic arch is located to the right of trachea. The left subclavian artery (LSA) originates from the proximal descending aorta and courses to the left behind the esophagus. In 60 percent cases there is dilatation of origin of the LSA (aortic diverticulum of Kommerell). It is commonly an asymptomatic finding with only 5 percent patients having symptoms.2 However, this anomaly may be associated with a constricting left ligamentum arteriosum, forming a vascular ring and causing airway compression. If the ligamentum arteriosum connects to LSA it forms a loose vascular ring, while if it extends to the aortic diverticulum of Kommerell, a tight ring is formed. On frontal radiograph there is aortic arch indentation on the right wall of the trachea with tracheal deviation to the left (Figs 8.10A to C). Right sided descending aorta may also be seen. Lateral view reveals indentation on the posterior aspect of trachea. On barium swallow, frontal views show a filling defect coursing from right inferior to left superior. On lateral view, there is posterior esophageal indentation. Cross-sectional imaging is indicated when there is clinical or radiographic evidence of airway compression. Midline descending aorta: In this anomaly the descending aorta is positioned immediately anterior to the vertebral body, instead of the normal left paravertebral location. It may be an isolated lesion or be associated with hypoplastic right lung and hence mediastinal shift; or aortic arch anomalies. Malposition may result in airway compression due to crowding of structures. Radiographs are often normal, cross-sectional imaging reveals the diagnosis.

Vascular Malformations Vascular malformations may be venous, lymphatic, or mixed venolymphatic. Although these lesions are usually soft and compressible, giant malformations of the neck and/or chest can compress airway.

Figs 8.10A to C: Right sided aortic arch: Chest radiograph (A) of a 5-year-old boy reveals a right sided aortic arch with hyperlucent left lung. CECT chest (B) shows indentation on the right wall of the trachea by the arch with an aberrant left subclavian artery (arrow).The descending aorta is in midline (C)

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Fig. 8.11: Esophageal atresia: CECT of a neonate with esophageal atresia, performed to evaluate respiratory distress shows the dilated proximal esophageal pouch (white arrow) causing significant compression of the trachea (black arrow)

Bronchopulmonary foregut malformations: Bronchogenic cysts are among commonest cystic lesions in the pediatric chest. The commonest location is around the carina. Hence, when large, these result in compression of the proximal bronchi. They can occur anywhere along the respiratory tract.4 The dilated proximal esophageal pouch in patients of esophageal atresia can also exert a mass effect on the adjoining airway4 (Fig. 8.11). Inflammatory causes: Deep neck space infections,when they spread into the mediastinum, can compress the airway. Large paravertebral abscesses, even tubercular may result in significant airway compression (Fig. 8.2). Mediastinal lymphadenopathy, tubercular or fungal infections can also narrow the airway by mass effect (Figs 8.12A to D). Masses: Lymphoma is the commonest childhood neoplasm to cause symptomatic airway compromise in children.11 Other neoplasms that tend to narrow the airway by extrinsic mass effect include infantile hemangiomas, germ cell tumors, rhabdomyosarcomas and neurogenic tumors (Figs 8.13A and B).

Intrinsic Causes Intrinsic causes include those involving the wall which may be dynamic (tracheomalacia) or fixed (stenosis) and intraluminal lesions. Wall Abnormalities Tracheomalacia: Tracheomalacia refers to abnormal softening of the trachea due to abnormality of the cartilaginous rings. This results in intermittent (expiratory) collapse of the trachea. The narrowing of the tracheal lumen is most marked during forced expiration, coughing, or the Valsalva maneuver.4 It may be primary

or secondary to compression by masses or vascular structures. Similar condition may involve the proximal bronchi. It may be congenital associated with syndromes such as cystic fibrosis, or even result from chronic inflammation, chronic extrinsic compression or prior intubation. The characteristic clinical presentation is of an expiratory wheeze. The diagnosis cannot be made on the basis of a single radiograph. Fluoroscopy, and typically fibreoptic bronchoscopy can demonstrate the characteristic dynamic collapse of the trachea. Airway fluoroscopy done in a lateral projection is the traditional radiographic method of diagnosing tracheomalacia. However, bronchomalacia is difficult to diagnose on fluoroscopy, and controlled-ventilation CT, cine CT, or cine MR imaging are preferred methods for this entity.4 On a single phase inspiratory CT the diagnosis is difficult, although the trachea may demonstrate an abnormal shape being flattened slightly posteriorly in the membranous part1,2 (Figs 8.14A to C). Paired inspiratory-expiratory MDCT/cine MDCT is more sensitive to demonstrate the expiratory collapse, and require the measurement of the area of trachea in both the phases.12 Stenosis: Fixed trachea stenosis may be congenital or acquired. Congenital tracheal stenosis results from absence of the membranous portion of the trachea resulting in complete or near complete cartilaginous tracheal rings. The various patterns of tracheal stenosis include generalized stenosis, carrot- or funnelshaped segmental stenosis, and focal stenosis. Focal stenosis usually involves the lower trachea. A tight focal stenosis causes more severe symptoms than a long, mild stenosis. It may be associated with congenital heart disease, pulmonary sling, TEF, or skeletal abnormalities.2,4 On axial imaging, trachea appears as a round or complete circle (O-shaped). Other findings include: circumferential narrowing of the entire length of the trachea and fusion of the cartilaginous tracheal rings posteriorly.4, 13 Congenital tracheal web is a rare entity. The web is usually not associated with deformity of the tracheal cartilage or the tracheal wall. CT reveals a weblike structure traversing and narrowing the tracheal lumen,14 which is well demonstrated on coronal reformatted images and virtual bronchoscopy.4 Bronchopulmonary foregut malformations: Bronchopulmonary foregut malformations include a wide spectrum of disorders such as: tracheal agenesis, tracheal stenosis, tracheal fistula, branching anomalies, bronchial stenosis, or lung agenesis and hypoplasia; as well as bronchogenic cysts are also included in this group.3 These anomalies may present with respiratory distress in the newborn, recurrent pulmonary infections or mass lesions later in life. This chapter deals with anomalies affecting the major bronchi. Bronchial atresia and sequestration: Bronchial atresia most often involves the left upper lobe. On CT, a mucocele is identified as a hypo- or fluid-attenuating branching structure distal to the atretic bronchus near the hilum. The pulmonary parenchyma distal to the atretic segment is often lucent and demonstrates air trapping. The affected region may even be outlined by pseudofissures.4 Bronchial atresia may be isolated or associated with a retained systemic vascular connection, when it is referred to as intralobar

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Figs 8.12A to D: Tubercular lymphadenopathy: CECT of a 6-year-old boy reveals conglomerate, necrotic, calcific mediastinal lymphadenopathy with left upper lobe consolidation (A). A more caudal section mediastinal window (B), and lung window (C) and minIP (D) show narrowing of the left main (arrow) and upper lobe bronchii.

sequestration. The imaging appearance is virtually identical to that of isolated bronchial atresia, except that the atretic bronchus is ectopically located at the margin of the lung. Rarely, such ectopic bronchi may not be atretic but have a connection with the gastrointestinal tract, usually the esophagus. Such cases are usually accompanied by bronchiectasis and accumulated secretions from impaired clearance of lung parenchyma. It is hence important to look for airway abnormalities, pulmonary parenchymal abnormalities, retained systemic vascular connections, anomalous pulmonary venous drainage, and airway communication with the gastrointestinal tract in patients with suspected bronchopulmonary foregut malformations.4, 15,16 Tracheo-esophageal fistula (TEF): Esophageal atresia with or without TEF is believed to result from a faulty separation of the

embryonic trachea and esophageal remnants. The commonest type of these is proximal esophageal atresia with distal TEF (up to 80–90%). H-shaped TEFs with no atresia constitute up to 5–8 percent.4 Typical clinical presentation includes failure to pass a feeding tube in a newborn with a history of polyhydramnios at prenatal US, excessive secretions from the mouth, and respiratory distress.4 Chest radiograph demonstrates the feeding tube catheter ending/coiling in the proximal thoracic esophagus. The presence of air in the distal gastrointestinal tract confirms the presence of a distal TEF. In such patients, it is important to observe the airway as there is frequently associated tracheomalacia.17 Also, a dilated proximal esophageal pouch can result in airway compression. Patients with H type fistula may present with recurrent aspiration or small airway disease. While contrast esophagogram is the

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Figs 8.13A and B: Neuroblastoma: CECT (A) showing a large posterior mediastinal mass lesion causing displacement and compression of the major bronchi, especially the left main bronchus. Lung window (B) reveals a hyperlucent left lung

Figs 8.14A to C: Tracheomalacia : Axial CT (A) of a neonate with stridor showing slight posterior flattening of the trachea. min IP (B) and VRT images (C) show narrowing of subglottic trachea. On bronchoscopy, this narrowing was found to be dynamic

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Figs 8.15A and B: Tracheoesophageal fistula (TEF): Axial CT (A) of an infant reveals a communication between the trachea and esophagus with right upper lobe consolidation. Coronal MPR (B) also demonstrates the fistula

Figs 8.16A and B: Tracheal bronchus: Axial lung window (A), coronal MPR (B) reveal an accessory bronchus arising from the trachea and aerating the posterior segment of right upper lobe (arrows)

investigation of choice, CT scan may demonstrate the fistula (Figs 8.15A and B). Tracheobronchial branching anomalies: Tracheobronchial branching anomalies may be seen as an isolated finding or accompanying heterotaxy syndromes, pulmonary sling, and conditions associated with pulmonary underdevelopment (agenesis, aplasia or hypoplasia). The commonest amongst these is the tracheal bronchus or “pig bronchus” (Figs 8.16A and B). A tracheal bronchus arises from the trachea or mainstem bronchus and aerates either the entire upper lobe or a segment.4,18 An accessory cardiac bronchus or tracheal diverticulum are also

relatively common anomalies. An accessory cardiac bronchus arises from the medial wall of the right mainstem bronchus or bronchus intermedius, grows toward the pericardium terminating as a blindending stump or branching further.19 Tracheal diverticula is seen arising with a narrow stalk from the right posterolateral wall of the trachea near the thoracic inlet.4 Other abnormal branching patterns include tracheal trifurcation, bilateral right-sided isomerism or bilateral left-sided isomerism. A detailed classification of tracheobronchial branching anomalies has been given in “Imaging of the tracheobronchial tree” in AIIMS-MAMC-PGI Imaging Course Series, Diagnostic Radiology-Chest and Cardiovascular Imaging 3rd edition.20

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Metabolic conditions: Hunter syndrome (a mucopolysaccharidosis) may cause the deposition of mucopolysaccharides in the walls of the major airways results in progressive airway narrowing due to wall thickening and anteroposterior collapse.4, 21 Acquired: Acquired tracheal or bronchial strictures usually result from chronic inflammation, often tubercular (Figs 8.17A to E). Another cause of acquired airway strictures is posttraumatic sequelae.

Intraluminal Causes A foreign body (FB) is the most common cause of bronchial obstruction. Soft tissue masses of the trachea and bronchi are rare. Foreign body: Foreign body aspiration is most often seen in infants and toddlers (8 months-3 years). The bronchi are the most common site of lodgement (76%), while laryngeal (6%) or tracheal (4%) lodgement is far less common. Right bronchus is more common (58%), than the left (42%).2 The clinical presentation may be acute, while more often the symptoms remain indolent. The symptoms and signs can mimic asthma, upper respiratory infection, or pneumonia. The history of aspiration is often not elicited. Foreign body may lead to partial (“ball-valve” effect) or complete obstruction, resulting in hyperinflation or collapse respectively. Chest radiograph findings include asymmetric lung aeration, lung consolidation or atelectasis, and even pneumothorax or pneumomediastinum1 (Figs 8.18 and 8.19). Metallic foreign bodies can be identified on plain radiographs (Fig. 8.18). However, commonly aspirated airway foreign bodies are food products, particularly nuts, and seeds, which are not radio-opaque enough to be identified at conventional radiography (Figs 8.20A to D). These organic materials can swell following absorption of water and then rapidly change a partial airway obstruction to a complete obstruction.4 Inspiratory radiographs alone may be normal in up to a third of patients (14-35%) with foreign bodies.1,2 The lung volume of the affected lung/segment may be normal, increased or decreased.1,2 Majority (up to 97%) of the foreign bodies are non-radiopaque.1 The characteristic radiographic finding is that the lung volume remains static with no change in different phases of respiration. This can be demonstrated by obtaining paired inspiratory expiratory radiographs in cooperative children. In infants and uncooperative children bilateral decubitus radiographs of the chest or fluoroscopy can demonstrate the same finding.1,2 The differential diagnosis of an asymmetric, lucent lung include Swyer-James syndrome and pulmonary hypoplasia.1,2 However, air trapping may be seen in partial obstruction. CT is not routinely advocated in evaluation of a bronchial foreign body. It may, however, be performed as work-up for nonresolving pneumonia or collapse, or even stridor (Fig. 8.20) . CT is also a good option when the clinical setting does not strongly warrant bronchoscopy or if bronchoscopy is not readily available.4 On CT, foreign bodies are well demonstrated as filling defects in the bronchus, besides detailing the changes in the distal lung. It can identify both opaque and non-opaque foreign bodies. Kosucu

et al reported a 100 percent sensitivity and specificity of CT in the evaluation of endobronchial foreign bodies.22 Applegate et al while evaluating low-dose helical CT found a sensitivity of 83 percent and specificity of 89 percent for visualizing plastic pieces in the airway. Peanuts however were not well visualized in the same study.23 Even esophageal foreign bodies can present acutely with symptoms related to airway compression or with complications consequent to perforation and neck and/or mediastinal infection.4 Inflammatory: Tuberculosis- Occasionally, enlarged lymph nodes erode into the bronchus and result in endobronchial fibrosis or luminal occlusion. Intraluminal granulomas may occur in the trachea or bronchi.4,24 In a series by Weber et al, airway involvement in tuberculosis was seen in upto 30 percent cases.25 Tumors: Tracheal soft tissue tissue masses include tracheal papilloma; while bronchial masses may be carcinoid tumors.1 Carcinoid tumor is the most common amongst these. Rare lesions include adenoid cystic carcinoma, mucoepidermoid carcinoma, inflammatory myofibroblastic tumor, juvenile xanthogranuloma, and metastasis.4 Carcinoid tumors comprise about 80 percent of endobronchial neoplasms in children and adolescents. These present in children or young adults and may be associated with neuroendocrine secretion.3, 26 Most carcinoid tumors occur in the mainstem or lobar bronchi, and patients present with dyspnea, wheezing, cough or hemoptysis. CT reveals typically intensely enhancing, ovoid lesions with a long axis parallel to the bronchovascular bundle.4 These lesions may have intraluminal, mural, and extrabronchial components. Associated collapse, consolidation, or air trapping is often seen (Figs 8.21A to C). They are relatively slow growing masses, and complete surgical resection offers the best chance of cure.27,28

Peripheral Airways Bronchiolitis/Small Airway Disease Acute: Acute inflammation of the bronchi and bronchioles is common in children, and is most often infective in etiology. Plain radiographs reveal hyperinflation with increased perihilar markings. This entity is covered in detail in the chapter on Pulmonary Infections. Chronic: The causes of chronic, small airway disease in children include: constrictive bronchiolitis, extrinsic allergic bronchiolitis, diffuse panbronchiolitis, follicular bronchiolitis and lung disease of prematurity.3 The chest radiograph and even CT findings are often nonspecific though the underlying etiologies may be quite variable. CT scan reveals ground glass opacities with mosaic attenuation and air trapping. Mild bronchiectasis with bronchial wall thickening may be seen (Figs 8.22 and 8.23). Constrictive bronchiolitis or bronchiolitis obliterans: Although constrictive bronchiolitis may present as a unilateral hyperlucent lung (Swyer James Syndrome), it is more often bilateral. There are

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Figs 8.17A to E: Inflammatory stricture: Cranial to caudal CECT sections (A-C) reveal narrowing of the left main and lower lobe bronchii with ill defined surrounding soft tissue and collapse of left lower lobe. VB images (D) also confirm the main bronchus stricture with non-visualization of the distal airway. Coronal min-IP (E) shows a long segment involvement (For color version Fig. 8.17D see plate 1)

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Fig. 8.18: Foreign body: Chest radiograph demonstrates a radiopaque foreign body in the right lower lobe bronchus with consolidation in the distal lung

Fig. 8.19: Foreign body: Chest radiograph of a 2-year-old boy with history of foreign body aspiration and sudden onset respiratory distress reveals a hyperinflated left lung with spontaneous pneumothorax (arrows) and extensive subcutaneous emphysema

Figs 8.20A to D: Foreign body: Chest radiograph (A) of a toddler with history of recurrent high grade fever reveals a hyperinflated left lung with tramtrack lesions in the left lower zone. A subsequent chest radiograph (B) shows progression in the lung parenchymal lesions with decrease in the hyperinflation. CT scan (C,D) reveals abrupt cut-off of the left main bronchus with intraluminal contents, and distal bronchiectasis. A “neem fruit ball” was removed from the left main bronchus on bronchoscopy

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Figs 8.22A and B: Chronic bronchiolitis : Axial CT lung window (A) and minIP (B) of a 3-year-old girl with history of dyspnea reveals prominent mosaic attenuation with air-trapping and mild bronchiectasis

several causes of this entity including infection (viral or mycoplasma), toxic and fume exposure, collagen vascular diseases such as Rheumatoid arthritis; and complication of bone-marrow or heart-lung transplant.3,29 HRCT reveals a prominent mosaic attenuation with bronchial abnormalities including bronchiectasis; and air-trapping3, 30 (Figs 8.22A and B). The pattern is similar to severe asthma or cystic fibrosis. Figs 8.21A to C: Carcinoid tumor: CT scout (A) of a 16-year-old boy with history of recurrent pulmonary infections reveals volume loss of left lung with extensive consolidation and bronchiectasis. Axial CECT (B) shows a homogeneous mass in the left main bronchus with mediastinal shift to left. minIP (C) demonstrates the entire extent of the mass with distal lung changes. Histopathology revealed a carcinoid tumor

Extrinsic allergic alveolitis: Extrinsic allergic alveolitis or hypersensitivity pneumonitis is a form of cellular bronchilitis. In the acute stage CT reveals multiple, ill-defined centriliobular nodules; while in the subacute or chronic stage mosaic alternation with expiratory air trapping are seen3, 29 (Figs 8.23A and B). Areas of fibrosis may also be present.

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Figs 8.23A and B: Chronic bronchiolitis : HRCT (A and B) of 8-year-old child reveals multiple, ill-defined centriliobular nodules and bronchial wall thickening (arrow)

Diffuse pan-bronchiolitis: Diffuse pan-bronchiolitis is an exudative form of bronchiolitis seen in Eastern and South-Eastern Asia. CT reveals multiple small centrilobular nodules and linear opacities diffusely distributed in both the lungs.3 Follicular bronchiolitis: Follicular bronchiolitis or lung hyperplasia of the bronchus associated lymphoid tissue is also a cause chronic obstructive diffuse lung disease. In addition to expiratory air trapping, CT reveals areas of ground glass opacity.3, 31

Lung Disease of Prematurity This is a unique form of airway disease seen in premature infants with bronchopulmonary dysplasia. It is a destructive diffuse lung disease occurring in a background of rapid alveolar growth. CT helps in excluding other causes of chronic respiratory distress such as central airway lesions.3

Figs 8.24A to C: Cystic fibrosis: CT scout (A) of a 16-year-old girl showing tubular, branching opacities in the right lung with paratracheal adenopathy. CT scan (B and C) reveals areas of fibrosis, bronchiectasis, bronchial wall thickening, air trapping and mucus plugging

Chapter 8 ™ Pediatric Airway

Figs 8.25A and B: Bronchiectasis: Chest radiograph (A) showing cystic lucencies with air-space nodules in the right lower zone suggesting secondary infection. CT scan (B) at a different date shows tubular and cystic bronchiectasis in right lower lobe with air trapping

Bronchiectasis Bronchiectasis is a common cause of respiratory symptoms in children.28 It is often the result of chronic inflammation causing damage to the supporting structure of the airways. Also, chronic or recurrent inflammation due to immunodeficiency states may cause bronchiectasis. Other etiologies include, abnormal mucus as in cystic fibrosis and abnormal mucociliary clearance in children with ciliary dyskinesias (Figs 8.24A to C). Proximal bronchial obstruction due to an intrinsic or extrinsic cause may also lead to bronchiectasis in the distal lung. Aspiration secondary to gastroesophageal reflux due to its chronic, recurrent nature has also been postulated as a cause of bronchiectasis.3,32 Patients typically present with recurrent infections. Chest radiographs are relatively insensitive in detecting early changes,

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Figs 8.26A and B: Asthma: CT scout (A) showing relative hyperlucency of left lower zone. CT scan (B) shows multiple areas of air trapping

with HRCT being the imaging modality of choice. 3 Chest radiographs reveal multiple cystic, ring or tram-track lucencies with bronchial wall thickening. In case of secondary infection mucous plugging, air-fluid levels, bronchial wall thickening and even enlarged draining nodes may be seen (Figs 8.24 and 8.25).

Asthma The peak age of prevalence of asthma in children is 6 to 11 years, with a male predominance. Thirty percent of these persist into adulthood.2 Chest radiographs are usually normal and are indicated in case of poor response to therapy, suspected complications or suspicion of an alternate diagnosis.2 Radiographs reveal hyperlucency of lungs or foci of atelectasis. The differential diagnosis includes viral bronchiolitis. CT is seldom indicated in asthma and reveals non-specific findings of small airway disease (Figs 8.26A and B). Findings of secondary allergic

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REFERENCES

Figs 8.27A and B: ABPA: Chest radiograph (A) of a 16-year-old asthmatic boy showing multiple tubular, branching opacities in bilateral lung fields giving a “finger-in-glove” appearance. CT scan (B) confirms the presence of bilateral tubular bronchiectasis with bronchoceles

bronchopulmonary aspergillosis (ABPA) may be seen (Figs 8.27A and B). Complications are more frequent in younger children as their bronchi are smaller and more easily occluded in an exacerbation. Complications include: lobar collapse, segmental or subsegmental atelectasis, pneumonia, air leaks (pneumomediastinum, subcutaneous emphysema and rarely pneumothorax or pulmonary interstitial emphysema (PIE). In conclusion, it is critical to evaluate the airway in all children presenting with acute, chronic or recurrent respiratory symptoms. Multiphasic imaging is essential. Plain radiographs and fluoroscopy form the initial methods of evaluation, with CT being required often for a complete diagnosis.

1. ‘Airway’ in Fundamentals of Paediatric Radiology LF Donnelly 2001 Saunders, Philadelphia, USA. 2. ‘Airway’ in Diagnostic imaging Paediatrics. LF Donnelly (Ed). Amirsys, Utah, USA, 2005. 3. Long FR. Paediatric airway disorders : Imaging evaluation. Radiol Cl N Am RCNA 2005; 43:371-89. 4. Yedururi S, Guillerman R P, Chung T, et al. Multimodality Imaging of Tracheobronchial Disorders in Children Radiographics 2008; 28(3):e29. 5. Dinesh Kumar, S, Ashu Seith, Raju Sharma, et al. Unpublished data AIIMS, Postgraduate Thesis - Evaluation of tracheobronchial lesions by multi-detector row CT” 2003-06. 6. Suto Y, Tanable Y. Evaluation of tracheal collapsibility in patients with tracheomalacia using dynamic MR imaging during coughing. Am J Roentgenol (AJR) 1998; 171:393-4. 7. John SD, Swischuk LE. Stridor and upper airway obstruction in infants and children. Radiographics 1992; 12:625-43. 8. Bitar MA, Moukarbel RV, Zalzal GH. Management of congenital subglottic hemangioma: trends and success over the past 17 years. Otolaryngol Head Neck Surg 2005; 132:226-31. 9. Choo KS, Lee HD, Ban JE, et al. Evaluation of obstructive airway lesions in complex congenital heart disease using composite volumerendered images from multislice CT. Pediatr Radiol 2006; 36:219-23. 10. Swischuk LE. Cardiovascular system: imaging of the newborn, infant and child. 5th ed. Philadelphia, Pa: Lippincott Williams &Wilkins, 2003; 303-17. 11. Glick RD, La Quaglia MP. Lymphomas of the anterior mediastinum. Semin Pediatr Surg 1999; 8:69-77. 12. Lee EY, Litmanovich D, Boiselle PM. Multidetector CT evaluation of tracheobronchomalacia Radiol Clin N Am 2009; 47(2):261-69. 13. Berrocal T, Madrid C, Novo S, Gutierrez J, Arjonilla A, GomezLeon N. Congenital anomalies of the tracheobronchial tree, lung, and mediastinum: embryology, radiology, and pathology. Radiographics 2004; 24:e17. 14. Legasto AC, Haller JO, Giusti RJ. Tracheal web. Pediatr Radiol 2004; 34:256-8. 15. Langston C. New concepts in the pathology of congenital lung malformations. Semin Pediatr Surg 2003; 12:17-37. 16. Newman B. Congenital bronchopulmonary foregut malformations: concepts and controversies. Pediatr Radiol 2006; 36:773-91. 17. Swischuk LE. Alimentary tract, imaging of the newborn, infant and child. 5th ed. Philadelphia, Pa: Lippincott Williams &Wilkins, 2003; 350-6. 18. Ghaye B, Szapiro D, Fanchamps JM, Dondelinger RF. Congenital bronchial abnormalities revisited. Radiographics 2001; 21:105-119. 19. McGuinness G, Naidich DP, Garay SM, Davis AL, Boyd AD, Mizrachi HH. Accessory cardiac bronchus: CT features and clinical significance. Radiology 1993; 189:562-6. 20. Ashu Seith Bhalla, Raju Sharma. Imaging of the tracheobronchial tree in AIIMS-MAMC-PGI Imaging Course Series, Diagnostic Radiology-Chest and Cardiovascular Imaging, 3rd edn, Jaypee Publishers, New Delhi 2009; 90-116. 21. Davitt SM, Hatrick A, Sabharwal T, Pearce A, Gleeson M, Adam A. Tracheobronchial stent insertions in the management of major airway obstruction in a patient with Hunter’s syndrome (type-II mucopolysaccharidosis). Eur Radiol 2002; 12:458-62. 22. Kosucu P, Ahmetoglu A, Koramaz I, et al. Low-dose MDCT and virtual bronchoscopy in pediatric patients with foreign body aspiration. Am J Roentgenol AJR 2004; 183:1771-7.

Chapter 8 ™ Pediatric Airway 23. Applegate KE, Dardinger JT, Lieber ML, et al. Spiral CT scanning technique in the detection of aspiration of LEGO foreign bodies. Pediatr Radiol 2001; 31:836–40. 24. Sima Mukhopadhyay, AK Gupta, Ashu Seith. Imaging of tuberculosis in children in essentials of tuberculosis in children 3rd edn, Vimlesh Seth, SK Kabra (Eds) Jaypee Brothers, New Delhi 2006; 375-404. 25. Weber AL, Bird KT, Janower ML. Primary tuberculosis of childhood with particular emphasis on changes affecting the tracheobronchial tree. Am J Roentgenol AJR 1968; 103:123-32. 26. Ferretti GR, Thony F, Bosson JL, et al. Benign abnormalities and carcinoid tumors of the central airways:diagnostic impact of CT bronchography. Am J Roentgenol AJR 2000; 174:1307-13.

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27. Curtis JM, Lacey D, Smyth R, Carty H. Endobronchial tumours in childhood. Eur J Radiol 1998; 29:11-20. 28. Kothari NA, Kramer SS. Bronchial diseases and lung aeration in children. J Thorac Imaging 2001; 16:207-23. 29. Hansell DM. Small airways disease: detection and insights with computed tomography. Eur Respir J 2001; 17:1294-1313. 30. Lau DM, Siegel MJ, Hildebolt CF, et al. Bronchiolitis obliterans syndrome: thin section CT diagnosis of obstructive changes in infants and young children after lung transplantation. Radiology 1998; 208:783-8. 31. Kinane BT, Mansell AL, Zwerdling RG, et al. Follicular bronchitis in the paediatric population. Chest 1993; 104:1183-6. 32. Patterson PE, Harding SM. Gastroesophageal reflux disorders and asthma. Curr Opin Pulm Med 1999; 5:63-67.

SECTION 3—GASTROINTESTINAL AND BILIARY TRACT, LIVER AND PANCREAS

chapter 9

Developmental Anomalies of Gastrointestinal Tract Alpana Manchanda, Sumedha Pawa

Derangement of embryological development can lead to malformations at any point along the gastrointestinal tract (GIT) from the oropharynx to the anorectum. Most of these abnormalities manifest clinically with GIT obstruction and present with vomiting and abdominal distention. Bile-stained vomiting occurs when the obstruction is below the ampulla of Vater, whereas vomiting of clear gastric contents indicates obstruction above the second part of the duodenum. Abdominal distention indicates a low level of obstruction. However, one must remember that both vomiting and abdominal distention may occur in conditions like sepsis, increased intracranial pressure, etc. in the absence of anatomic abnormality of the GI tract.1 Infants who have undergone resuscitative efforts, or infants on continuous positive airway pressure, may swallow an excessive amount of air, leading to clinically significant abdominal distention. Since the distention is by air only, the walls of the distended loops on the abdominal radiograph are razor-sharp. Pathological conditions, involving the gut, such as ileus and obstruction, are characterized by dilatation with both air and fluid.2 Developmental lesions of the neonatal gastrointestinal tract can be grouped as follows:1

Anatomical Attributed to embryological maldevelopment • Esophageal atresia with or without fistula • Antropyloric atresia • Antral diaphragm • Duodenal atresia • Duodenal stenosis – Intrinsic: Windsock duodenum – Extrinsic: Annular pancreas – Midgut malrotation with peritoneal bands • Anorectal atresia. Attributed to in utero catastrophic (ischemic) complication • Jejunoileal atresia • Colonic atresia or stenosis • Complicated meconium ileus. Functional • Meconium plug syndrome and its variants • Megacystis-microcolon-intestinal hypoperistalsis.

Combined Anatomical-Functional • Hypertrophic pyloric stenosis • Midgut volvulus (complicating midgut malrotation) • Uncomplicated meconium ileus • Colonic aganglionosis (Hirschsprung’s disease). IMAGING MODALITIES The imaging methods available to investigate the gastrointestinal tract in the neonate include, plain film radiography, ultrasonography and contrast studies of the GI tract. Nuclear scintigraphy, computed tomography and magnetic resonance imaging are uncommonly required in infants.1 Plain Film Radiography It is the simplest, usually the first and sometimes the only examination performed. An anteroposterior supine radiograph may be sufficient only if the purpose is to evaluate a palpable mass or the presence of calcification. If obstruction is suspected, additional films are required. A cross-table lateral projection with the infant in supine position is best in terms of leaving the patient virtually undisturbed. However, a left-lateral decubitus view with a horizontal beam has the advantage of better identification of free gas over the liver and better anatomical definition of bowel loops in a frontal projection. If only one film is desired, a prone radiograph will give the most information regarding free gas as well as defining the level of obstruction. Occasionally, a prone lateral film is valuable for detection of gas in the rectum.1 Within seconds after birth, air enters the gastrointestinal tract and it can be seen radiographically in the stomach. Air is seen in the small bowel within the first hour, it reaches the cecum within 3 to 4 hours, and appears in the sigmoid colon by 11 hours. Gas fluid levels are generally absent except in the stomach and occasionally in the right colon. The normal bowel gas pattern in neonates is quite different from that seen in older children and adults. It is characterized by gas throughout the small and large bowel and little fluid with respect to air, so that bowel-air interfaces are thin and sharp, with few if any loops identified; rather, the gas distribution is one of multiple, closely apposed, rounded or polyhedral structures. Small and large bowel cannot be distinguished.2

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Figs 9.1A and B: Plain X-ray abdomen erect view reveals (A) few (three) air-fluid levels in proximal small bowel with absence of distal air diagnostic of a high small bowel (jejunal) obstruction in a newborn presenting with bilious vomiting. (B) In contrast, multiple air-fluid levels seen in another neonate with abdominal distention, is indicative of a low small bowel (ileal) obstruction

A gasless abdomen after the first few hours of life is occasionally seen in normal infants as well as in those with uncontrollable vomiting, continuous gastric aspiration, severe dehydration, esophageal atresia without a fistula and deficient air swallowing, secondary to CNS depression. Obstruction is manifested by distention of portion of the GI tract proximal to the obstruction, with little or no gas below. By observing the number and distribution of distended bowel loops and air fluid levels, one can estimate the approximate level of obstruction (Figs 9.1A and B).

Contrast Studies Air is the cheapest, easiest and most commonly available contrast medium. The presence of gas within the bowel can be very useful in delineating abnormalities, particularly a proximal high atresia. Occasionally, one may require to inject air to delineate the bowel better and it can be instilled by nasogastric tube or per rectum.3 Barium is not used in the following circumstances: (i) suspected perforation, where preferably a non-ionic contrast medium should be used; (ii) instances of lower small-bowel obstruction when retained fluid proximally is likely to cause oral barium suspension to precipitate and degrade the images; (iii) when a cleansing effect is also desired, as in attempted reduction of meconium ileus or meconium plug. Ionic water-soluble contrast media are ideal for stimulating evacuation of retained thick tenacious intestinal contents by virtue of their high osmolarity, which increases the intraluminal fluid and bulk. This, however, may cause water and electrolyte imbalance and appropriate patient hydration and electrolyte homeostasis should be carefully maintained. Ionic contrast media are contraindicated when investigating esophageal problems because aspiration may cause pulmonary edema. Non-ionic contrast media

are ideal for most of the circumstances. In suspected Hirschsprung’s disease, in which the rate of evacuation has some potential diagnostic value, barium should be preferred. The radiologist should modify the routine use of contrast as needed in a particular case.

Ultrasonography (US) Ultrasonography has been found to be highly accurate in the diagnosis of hypertrophic pyloric stenosis. It is useful in the diagnosis of gastric and duodenal duplications and in the detection of duodenal dilatation accompanying intrinsic or extrinsic duodenal obstruction, such as duodenal atresia and stenosis. Although duodenal dilatation is non-specific and additional contrast studies may be required to identify the specific cause, US is an excellent screening technique for localization of the site of obstruction. Ultrasound is valuable in the investigation of abdominal distention or palpable mass lesions because of easy and accurate detection of ascites as well as meconium peritonitis and intraperitoneal cystic lesions such as intestinal duplications and mesenteric or omental cysts.1 ESOPHAGUS Esophageal Atresia and Tracheoesophageal Fistula (TEF) Esophageal atresia with or without tracheoesophageal fistula is the most common congenital abnormality of the esophagus, manifesting itself during the neonatal period, occurring in about 1 in 2500 to 4000 live births.4 It is usually sporadic and its etiology is uncertain.3 No definite familial tendency has been documented in esophageal artesia, but more than one case in the same family has been noted.

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Fig. 9.2: Types of esophageal atresia/tracheoesophageal fistula. The plain radiographs for types A and B are similar as in case for types C and D

Embryology The trachea and esophagus develop from the common foregut during the early first trimester. During the fifth and sixth weeks of gestation, the common foregut divides into trachea and esophagus. Incomplete separation results in esophageal atresia with or without associated tracheoesophageal fistula. Because separation of the trachea and esophagus occurs cranial to tracheal branching of the carina, T-E fistulas generally present above the carina.5 Clinical Features The presentation is usually in the first few hours of life, with the newborn having excessive oral secretions, choking and sometimes even cyanosis. Typically, symptoms become more pronounced during the first feed. The abdomen may be distended due to air passing through the distal fistula into the stomach or may be scaphoid or gasless in patients who have atresia without a fistula or atresia with a proximal fistula. Patients with an H-fistula usually present later with history of choking while feeding, cough, cyanosis, recurrent or chronic pneumonias and a distended abdomen from tracheal gas passing through the fistula into the esophagus and stomach.5 Esophageal atresia may be diagnosed by antenatal ultrasound. It is suspected on the basis of maternal polyhydroamnios with an absent fluid filled stomach, the proximal esophageal pouch seen as a central anechoic area in the fetal neck or upper chest. The presence and size of the tracheoesophageal fistula determines the amount of fluid in the stomach and gastrointestinal tract. Associated anomalies in the other systems may be identified. The atresias may be multiple and involve the esophagus, duodenum and anus. Classification Esophageal atresia and tracheoesophageal fistula have been classified based on their anatomical and radiographic appearance, i.e. on the basis of presence (and location) or absence of a tracheoesophageal fistula (Fig. 9.2). They have been variously designated as types A to E (or 1 to 5) as follows3 Type A—Esophageal atresia without fistula (7.8%) Type B—Esophageal atresia with proximal fistula (0.8%) Type C—Esophageal atresia with distal fistula (85.8%)

Type D—Esophageal atresia with fistula in both the pouches (1.4%) Type E—H-type fistula without atresia (4.2%) In the majority of patients, the atresia occurs between the proximal and middle thirds of the esophagus with a gap of varying length between the atretic pouches.3 Most commonly, there is a proximal esophageal atresia with a distal tracheoesophageal fistula. This occurs in approximately 85.8 percent of cases. Next most common, occurring approximately in 7.8 percent cases, is isolated esophageal atresia. H-type fistula occurs in approximately 4.2 percent of cases. Esophageal atresia with proximal tracheoesophageal fistula or with both proximal and distal tracheoesophageal fistulas are quite rare.6 Approximately 50-70 percent of patients with esophageal atresia have additional anomalies. The VACTERL syndrome is seen in 15 to 30 percent of patients. “V” is for vertebral and vascular abnormalities. Of these, a right-sided aortic arch is seen in 5 percent cases. “A” is for anal and auricular malformations. “C” is for cardiac abnormalities like ventricular septal defects, patent ductus arteriosus and complex cyanotic heart disease. “TE” is for tracheoesophageal fistula and esophageal atresia. “R” represents renal abnormalities. “L” is for limb malformations.7

Imaging Features Plain film of the chest taken soon after birth reveals proximal esophageal pouch distended with air, thereby indicating the diagnosis on plain radiographs. In unequivocal cases, a thin soft rubber nasogastric tube is passed into the proximal pouch and about 5 cc of air is injected. A frontal radiograph of the chest showing dilated proximal esophageal pouch with round distal margin and coiled nasogastric tube within is diagnostic. The distended air filled proximal esophageal pouch may make visualization of the lower cervical and upper dorsal spine more clear. A lateral radiograph though not routinely indicated, if obtained, shows considerable anterior bowing and narrowing of the trachea by the dilated blind esophageal pouch.3 Plain radiograph of the chest should include the abdomen to evaluate the presence of air in the gastrointestinal tract. The presence of air in the stomach and the small bowel indicates esophageal atresia with a distal tracheoesophageal fistula. Absence of air in the stomach eliminates the possibility of a distal fistula. The

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Figs 9.3A and B: Esophageal atresia: (A) Frontal radiograph of chest and abdomen showing a catheter in the proximal pouch. The abdomen is gasless. (B) Lateral film shows the tip of the nasogastric tube at the level of 4th dorsal vertebra

Fig. 9.4: Esophageal atresia with distal tracheesophageal fistula: Coiled nasogastric tube is seen in the proximal esophageal pouch. Air is seen in the stomach and bowel

possibility of proximal tracheoesophageal fistula, however, cannot be eliminated (Figs 9.3A, B and 9.4). Air confined to the stomach raises the possibility of associated duodenal atresia and necessitates a follow-up plain film examination. Routine contrast examinations are not required in the neonate with esophageal atresia and TEF.3 Use of radiopaque contrast in the proximal pouch should be avoided, owing to the possibility of aspiration. Swallowed air or air through nasogastric tube is usually adequate for the diagnosis and to demonstrate the extent of the proximal pouch. If positive contrast examination is needed then isotonic nonionic contrast medium should be used in minimal

amount under fluoroscopic monitoring. Immediately after the study, contrast should be aspirated out. Through H-type fistulas can be at any level, most are at the thoracic inlet, between C7 and T2 vertebral bodies. The connection is angulated superiorly from the esophagus to the trachea, thus accounting for the more precise but less popular appellation of the N-type fistula. (Fig. 9.5) The best way to demonstrate H-type tracheoesophageal fistula is with careful injection of contrast medium via a nasogastric tube, first placed at GE junction and then gradually withdrawing the nasogastric tube with simultaneous injection of contrast under fluoroscopic guidance at various levels of the esophagus. The main reason that the H-type TEF is inconstantaly patent is that the normal esophageal mucosa is quite redundant and usually occludes the esophageal side of the fistula. Normal active swallowing may not distend the esophagus sufficiently to allow passage of contrast into the fistula.8 The patient should be viewed in the lateral or steep prone oblique projection with the right side down. Care should be taken to separate tracheal and esophageal lumens during the study so that fistula is readily identified between them. If the contrast appears in the trachea or lungs, it is very important to be certain if the contrast went through a fistula or was aspirated. If in doubt, then the investigation must be repeated once the trachea is cleared of the contrast. The side of the aortic arch should be determined. This information is important to the surgeon because the surgical approach to the mediastinum for repair of esophageal atresia with a distal TEF is from the side opposite to the aortic arch. When plain radiograph fails to indicate the side of the arch, computed tomography or a cardiac ultrasound can localize the arch. H-type fistulas are commonly demonstrated by contrast studies. 3 However, bronchoscopy and endoscopy are more sensitive methods and may be indicated to confirm the diagnosis, especially in a symptomatic older child where the contrast esophagogram is normal.

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five vertebral bodies) between the proximal and distal esophageal segments. The growth of the esophageal segments during the first few months of life tends to lessen the gap, thereby making a delayed primary repair feasible. A gastrostomy is established for feeding in the meantime.

Fig. 9.5: Contrast esophagogram demonstrating an oblique tract of an H-type tracheoesophageal fistula arising from the anterior wall of the esophagus and passing cephalad to the posterior tracheal wall, with contrast filling the tracheobronchial tree

Computed tomography (CT) is occasionally used in the preoperative evaluation of neonates with TEF and has proved to be a noninvasive and quick investigation. As compared with conventional bronchoscopy or catheterization, CT does not require any general anesthesia. The improved spatial and temporal resolution of new generation of scanners facilitates assessment of such small defects such as TEF. Either direct sagittal acquisition or axial acquisition with multiplanar reconstruction may help in demonstrating the precise location of fistula and the length of the gap between esophageal segments. Alternatively, length of the atretic segment can be assessed by passing a feeding tube from above and a metal bougie from below, via a gastrostomy. The knowledge of the origin of the fistula is helpful to the surgeon not only in deciding the side of the thoracotomy (right or left), but also in anticipating the gap to be bridged. The most important advantage of CT is that both esophagus and trachea are seen in their natural (unstretched) positions, and the interpouch gap can be measured accurately.9 High resolution CT scan on a 64-slice CT scanner has shown to provide definitive diagnosis and help in surgical planning in a critically ill neonate with H-Type TEF by distending the esophagus with air (by means of nasogastric feeding tube) during CT acquisition. Such a maneuver has proved to be very useful in optimizing the visualization of the fistula which may be totally or partially closed by a valve like mucosal flap or by a spasm of the muscular layer of the esophagus.10 When there is a proximal fistula, it is located in the anterior wall of the esophagus. In esophageal atresia with a distal fistula, primary repair is possible as the length of the gap between the esophageal segments is usually short. When there is atresia with no distal fistula, there is usually a long gap (of the order of about

Radiological Evaluation of Postoperative Complications Most patients of isolated esophageal atresia and tracheoesophageal fistula do well following surgical repair. Nevertheless, complications following surgery do occur and can be grouped under early and late complications. The early complications include: (i) leakage at the anastomotic site (14-16%), (ii) esophageal stricture and (iii) recurrent fistula. Oral feeding is not started for 1 to 2 weeks following surgery, till the edema subsides. A contrast study of the esophagus should be performed prior to the institution of oral feeds. A low-osmolal nonionic contrast should be used as leakage at the anastomotic site and is the most commonly identified early complication of surgical repair. Anastomotic leak increases the risk of esophageal stricture in the future. Donnelly et al found that the appearance of an extrapleural fluid collection after esophageal atresia repair performed via an extrapleural approach was associated with a high incidence of anastomotic leakage.8 If an anastomotic leak is left untreated, it may eventually lead to diverticulum formation. Most anastomotic leaks have been seen to close spontaneously. Stricture is another common complication which can occur following esophageal atresia repair. Most often, the stricture or narrowing is slight at the site of anastomotic repair and may persist for years, even though the patient has no functional problem (Figs 9.6A and B). Those with true stricture at anastomotic site are symptomatic and generally respond to bougie dilatation, with reoperation generally not required. However, if a stricture is associated with gastroesophageal reflux, the stricture may not respond to dilatation if it continues to be exposed to the acidic gastric contents. Hence, patients with postoperative strictures should be evaluated for reflux by upper gastrointestinal series or pH monitoring. A tracheoesophageal fistula can recur (3-14% cases) again at the anastomotic site, following surgery and is believed to be related to anastomotic leakage with erosion into trachea caused by local inflammation. The late complications which can occur following repair of an esophageal atresia are dysmotitily, gastroesophageal reflux, tracheomalacia, rib fusion and scolosis. Dysmotility is present in nearly all patients who have had esophageal atresia. Gastroesophageal reflux is also commonly associated and has been reported in 40 to 70 percent of cases. Reflux is thought to be related to the shortening of the intra-abdominal portion of the esophagus, or occur secondary to the surgical repair. Reflux may lead to peptic esophagitis and is likely to be the cause of more distal strictures in those who have had a history of repaired esophageal atresia. Tracheomalacia is thought to occur due to chronic intrauterine compression of trachea by a distended upper esophageal pouch.

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Figs 9.6A and B: (A) Esophageal atresia with distal TEF in a neonate. Lateral radiograph shows contrast filled dilated proximal esophageal pouch bowing the trachea anteriorly. (B) Barium swallow following primary anastomosis of esophageal atresia demonstrates slight narrowing at the anastomotic site (D4 vertebral level). The child had mild respiratory distress with dysphagia

STOMACH Microgastria Congenital microgastria is an extremely rare anomaly in which fetal rotation of the stomach fails to occur. There is no differentiation into fundus, body, antrum and pyloric canal and the lesser and greater curvatures also do not develop.8 It is believed to occur as a result of atresia of normal foregut development in the fifth week of embryonal development. Microgastria is often accompanied by other congenital anomalies such as malrotation, asplenia, renal, limb, vertebral and cardiac anomalies (VACTERL syndrome). 4 The common association between microgastria and upper extremity limb reduction defects, has led to the term microgastria-limb reduction complex.8 The clinical presentation of microgastria depends on the stage at which gastric development has been arrested. On prenatal ultrasound it may mimic esophageal atresia due to failure to visualize a distended stomach. Postnatally, microgastria presents with postprandial vomiting, failure to thrive, developmental delay, growth retardation, malnutrition and aspiration pneumonia. Most of the symptoms are due to secondary gastroesophageal reflux (GER).4 An upper GI study shows a small tubular stomach in the midline. The esophagus is dilated and appears to take over the storage function of the small capacity stomach. The gastroesophageal junction is incompetent and GER is present. There is associated esophageal dysmotility, secondary to its massive dilatation.4 The treatment of microgastria depends on its severity. The less severe forms may be treated conservatively, with surgery reserved as the first line of treatment in severe cases. The surgical treatment

consists of creation of a Hunt-Lawrence pouch as a gastric reservoir, which allows for the secondary esophageal changes to resolve.4

DEVELOPMENTAL OBSTRUCTIVE DEFECTS Congenital gastric obstruction is rare, as unlike the esophagus, the stomach undergoes little alteration in form during development. Gastric obstruction in the newborn may be due to: 1. Gastric atresia 2. Pyloric stenosis 3. Pyloric/prepyloric membrane/Antral web. Gastric Atresia Isolated gastric atresia is very rare and accounts for less than 1% of all congenital obstructions.11 Almost all gastric atresias occur at the pylorus or antrum. They are thought to be due to localized vascular occlusion in fetal life and not to failure of recanalization of the intestinal tract.3 Gastric atresia is classified into three types:12 a. Complete atresia with no connection between the stomach and duodenum b. Complete atresia with the fibrous band connecting the stomach and duodenum, and c. A gastric membrane or diaphragm producing atresia. Gastric atresia may be familial or associated with epidermolysis bullosa. The newborn presents mainly with regurgitation of non-bilious vomitus within the first few hours after birth. As obstruction is complete, a plain radiograph of the abdomen reveals a “single bubble appearance” with marked dilatation of the stomach, proximal to the obstruction and absence of gas in the small bowel and colon. This appearance is diagnostic and

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most patients are taken directly to surgery without any contrast imaging.11

Pyloric Stenosis or Prepyloric Membrane or Antral Web A pyloric stenosis or prepyloric membrane or antral web is a rare cause of symptomatic gastric obstruction in the newborn.2 Patients with webs or stenosis of the pylorus, rather than complete atresia may present later in life or even in adulthood because the obstruction is incomplete. 8 The most common presenting symptoms are cyclic postprandial vomiting and episodes of transient vomiting.9 Radiographically, the stomach is dilated with varying degrees of distal air, the extent of which depends on the degree of obstruction. In patients with incomplete obstruction, webs are more common than stenosis.4 It is difficult to diagnose an antral web on imaging studies. On UGI barium studies, a web is seen as a thin, 2-3 mm, linear circumferential filling defect traversing the barium column producing a reduction in the antral lumen, with a normal pyloric canal.11 On ultrasound, the membrane may be visible if the stomach is filled with clear fluid and appears as echogenic band extending centrally from the lesser and greater curvatures in the prepyloric region. A mucus strand may be mistaken for an antral membrane. On the basis of clinical and radiographical findings, the definitive diagnosis of antral web can be made endoscopically.2 Ectopic Pancreas Ectopic pancreas is an uncommon anomaly in which pancreatic tissue is found in the antropyloric region, less commonly in the duodenum. It is seen as an incidental finding. Less commonly it can cause symptoms of pain, GI bleeding or obstruction.8 An upper GI study shows a smooth, dome shaped filling defect, 1-3 cm in diameter on the greater curvature of stomach, with central umbilication at times. Ectopic pancreatic tissue may produce intermittent obstruction if it prolapses into the pylorus.11 Hypertrophic Pyloric Stenosis (HPS) Hypertrophic pyloric stenosis (HPS) is a common developmental condition affecting young infants. The incidence of HPS is approximately 3 in 1000 live births and boys are affected four to five times more commonly than girls. There is a familial disposition. Affected patients usually present between 2 to 6 weeks of age, with projectile non-bilious vomiting. Other conditions that can manifest with non-bilious vomiting include pylorospasm, hiatus hernia and preampullary duodenal stenosis.13 HPS is never seen beyond 3 months of age, except reported in premature infants, in whom, enteral feeding has been started late.14 Diagnosis can be made on appropriate history and palpation of an ‘olive’ mass in the subhepatic region of an infant. The mass is reported to be seen in up to 80 percent of cases. Antral peristaltic waves can also be observed.3 HPS is characterized by hypertrophy of pyloric circular muscle and redundancy of the pyloric mucosa. However, its etiology is unknown. Possible causes include hypersecretion with

resulting duodenal irritation and pylorospasm. There is a constant association with hyperplasia of the antral mucosa.3 Recent work has confirmed that the pylorus is abnormally innervated, and suggested that a lack of nitric oxide synthetase may be responsible for the pylorospasm that leads to gastric outlet obstruction and muscular hypertrophy.5 In most cases, a clinical diagnosis can be confidently made. However, further investigation may be required when the diagnosis remains in doubt. The diagnosis of HPS can be established by either barium studies or US. Ultrasonography has replaced barium examination being non-invasive and its ability to visualize the pyloric muscle directly to obtain measurements of muscle thickness.15,16

Ultrasonography (US) Ultrasonography is the imaging modality of choice in an infant suspected of having pyloric stenosis, with a reported accuracy approaching 100%.13 The examination is typically performed with a high frequency linear transducer (>5MHz) as the stomach, pylorus and duodenum are very superficial in an infant.17 The gall bladder which is adjacent to the pylorus, serves as a good landmark.3 Longitudinal and transverse images through the pylorus are obtained with the infant in the right posterior oblique position while scanning the right upper quadrant just off the midline. In this position, any fluid in the fundus of the stomach moves into the antrum and pyloric region, distending these regions. The stomach should not be emptied prior to the examination as this makes identification of antropyloric area difficult. If there is inadequate distention of the antrum, the infant may be given a glucose solution or water, orally or via a nasogastric tube. If fluid is administered, it should be removed at the end of the examination to prevent further vomiting and the risk of aspiration. In addition, if there is lot of gas, scanning the baby in the prone position may help in visualization of the pyloric region.17 The US evaluation of HPS includes assessment of both morphological and quantitative features. The classic findings are of a thickened echo-poor pyloric muscle and an elongated pyloric canal.15,16,18 The thickened muscle is seen as two curved bundles of mixed but generally low reflectivity bulging into the base of the duodenal cap and gastric antrum. The mucosal echoes are seen as one or two central bright lines. On transverse images the hypertrophic pylorus has a doughnut appearance, representing the reflective central mucosa and submucosa surrounded by echopoor muscle. The hypertrophic muscle may look non-uniform on transverse scanning of the pylorus. This is related to the sonographic artifact of anisotropic effect because of the orientation of the muscle fibers.3 Other signs include exaggerated peristaltic waves that terminate at the pylorus, esophageal reflux and little if any gastric emptying. An experienced examiner can frequently make the diagnosis just by qualitative assessment of the thickness of the pyloric wall. The exact measurements that separate a normal pylorus from a hypertrophic one, are controversial.16,18-20 However, as a general guide, a pyloric canal length greater than 15 mm, muscle thickness

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Figs 9.7A and B: (A) Hypertrophic pyloric stenosis: Longitudinal ultrasound image showing an elongated thickened pylorus seen as two curved bundles of low reflectivity (m). The mucosal echoes are seen as central bright lines. gb – gallbladder shows sludge within. Minimal fluid is present around the stomach. (B) Transverse section shows the muscle thickness as an echo poor rim – “Bull’s eye” sign. Serosa to serosa measures 15 mm (cursors)

greater than 3.0 mm, and transverse serosa-to-serosa diameter greater than 15 mm is consistent with HPS. (Figs 9.7A and B). At least two values should be positive. A muscle thickness less than 2.0 mm is unequivocally normal. A muscle thickness between 2 and 2.9 mm is abnormal but non-specific, and can be seen in gastritis and pylorospasm as well as in HPS. Though pylorospasm may mimic HPS on sonography as there is some pyloric muscle thickening and/or slight elongation of the pyloric canal, pylorospasm is transient and generally resolves in 30 minutes. An important pointer for diagnosing pylorospasm is that there is considerable variation in measurement or image appearance with time during the study. 21 Borderline muscle thickness measurements are more likely to occur in premature than in term infants. A number of ancillary sonographic signs of HPS have been described.17 • “Shoulder sign” – refers to an indentation upon the gastric antrum produced by hypertrophy of the pyloric muscle • “Double tract sign” – this refers to fluid, trapped in the mucosal folds in the center of an elongated pyloric canal seen as two sonolucent streaks in the center • “Nipple sign” is produced due to the evagination of redundant pyloric mucosa into the distended portion of the antrum. Color Doppler evaluation of the pylorus may reveal hyperemia within the muscle and mucosal layers. False negative diagnosis may be made if the stomach is overdistended, because it can displace the pylorus posteriorly, making it difficult to visualize the pyloric canal. If the scan is not in the midline, or is tangential to the antrum, the antral wall can simulate a thickened pyloric muscle, leading to a false positive diagnosis.

Barium Study A barium study should be performed if ultrasound is inconclusive or gastroesophageal reflux is suspected.21 If gastric distention is severe, a nasogastric tube should be passed and the stomach emptied. With the patient in the prone oblique position, the tube is placed in the antrum and adequate barium is injected via the tube under fluoroscopic control and spot films are taken. Most of the infants, with and without HPS, show some degree of pylorospasm. In HPS, generally barium will pass through the antropyloric region within 1 to 10 minutes, but may be delayed as long as 20 to 25 minutes. The pyloric canal is narrowed (the “string sign”) and elongated and almost always curved upward posteriorly (Fig. 9.8). Combination of narrowing and elongation is the hallmark of HPS on barium study. Barium may be caught between folds overlying the hypertrophied muscle and parallel lines (the “double string sign”) may be seen (Fig. 9.9). The enlarged muscle mass looks much like an “apple-core lesion”, with undercutting of the distal antrum and proximal duodenal bulb. The “beak sign” is noted as the thick muscle narrows the barium column as it enters the pyloric canal. Virtually all of the above signs can be seen transiently in infants especially those with some degree of spasm. The study should be continued sufficiently long to document the persistence of the findings in order to assure the diagnosis of pyloric stenosis. Occasionally, an associated antral web or diaphragm may be identified. Adult Idiopathic Hypertrophic Pyloric Stenosis (AIHPS) It is a mild form of HPS which may rarely present later in adult life. Its exact incidence is not known, as majority of these patients are asymptomatic for years. Around 80 percent of patients with

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Fig. 9.8: Upper GI barium study in a child with pyloric stenosis. The markedly narrowed pylorus curves upward and posteriorly to the duodenal bulb which shows an impression of the hypertrophied muscle in the base

The radiologic and endoscopic studies may be non-specific. However, the diagnosis should be suspected if there is elongation of the pyloric canal and is accompanied by marked dilatation of the stomach. In AIHPS, the “string sign” may be seen as an extremely thin line of barium on an upper GI study. A marked thickening of the pyloric muscle may produce a convex indentation at the base of the duodenal bulb, causing a mushroom-like deformity (“Kirklin’s sign”). The presence of a barium filled cleft between the hypertrophied muscle and the fibers of the pylorus can project into either one or both sides of the pylorus, proximal to the base of the bulb (“Twining’s sign”). However, none of these signs are pathognomic and presence of two or more of them strengthens the radiologic diagnosis. Endoscopy may be useful and the classic finding that has been described is the “donut” or the cervix sign which consists of a fixed narrow pylorus with a smooth border. In the congenital type of HPS, pyloromyotomy is the preferred treatment. Normal emptying of the stomach occurs within 2-3 days after the procedure. However, muscle thickness gradually regresses to normal and may even take 6-8 weeks.3 In contrast, in AIHPS, pyloroplasty and recently, laparoscopic pyloromyotomy have been tried with successful results.22 An increased incidence of renal anomalies like pelviureteric junction obstruction, primary megaureter, duplex kidney, renal agenesis or ectopia and horseshoe kidney have been reported in patients with HPS.23

DUODENUM Duodenal obstruction is a relatively common form of intestinal obstruction in the newborn. It may be complete (duodenal atresia) or incomplete. Complete duodenal obstruction is seen more frequently than congenital gastric obstruction.11 Incomplete obstruction may be intrinsic, such as duodenal stenosis caused by a web or “windsock” membrane; or it is more often extrinsic, e.g. duodenal compression from bands, annular pancreas, etc. Intrinsic and extrinsic obstructions may coexist. Table 9.1: Causes of duodenal obstruction in the newborn

Fig. 9.9: Characteristic findings of HPS in a 6-week-old boy with history of vomiting: The pyloric canal is narrowed and elongated and the base of the duodenal bulb is stretched by the pyloric mass

the adult form of the disease are men which is in concordance with the male preponderance of congenital HPS. The primary form of AIHPS should be differentiated from the secondary form which is caused by diseases such as peptic ulcer disease, hypertrophic gastritis or malignancy.23 In AIHPS, the pylorus is bulbous or fusiform with its thickest portion at the pyloroduodenal junction. Patients present with symptoms of delayed gastric emptying not associated with any pain.

Intrinsic

Extrinsic

Duodenal atresia Duodenal stenosis Duodenal web or diaphragm

Ladd’s bands Midgut volvulus with malrotation Annular pancreas Duplication Preduodenal portal vein

Duodenal Atresia and Stenosis Atresia is much more common than stenosis, but the etiology is the same. Atresia or stenosis occurs when the duodenum, which is a solid tube till about 3 to 6 weeks’ gestation, fails to recanalize partially or completely. Unlike jejunal and ileal atresia, it does not appear to be related to intrauterine ischemia.11 Atresia and stenosis almost always occur in the region of the ampulla of Vater (about 80% are just distal to the ampulla); thus they are frequently

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demonstrate the obstruction, one can introduce through a nasogastric tube.12 However, a contrast enema in patients with complete duodenal obstruction may be done to exclude additional, more distal atresia.7 A microcolon implies that there is a distal atresia or atresias. The newborn with congenital duodenal obstruction, complete or partial, requires surgery and is frequently taken to surgery without any more radiological investigation other than the plain film. However, further radiological study is required for making a preoperative diagnosis, specifically to distinguish between a cause of partial obstruction for which operation may be delayed, such as duodenal stenosis, from midgut volvulus, which requires emergent surgery. In these cases, when the infant is clinically stable, an upper gastrointestinal (UGI) series may be very useful. On UGI study, duodenal stenosis appears as dilatation of the duodenum proximal to the point of obstruction with abrupt caliber change.3 Fig. 9.10: Duondenal atresia : Erect film of the abdomen demonstrating the “double bubble” sign

accompanied by abnormalities of the bile duct and pancreas. Annular pancreas occurs in 20 percent of patients with duodenal atresia or stenosis. It may contribute to the duodenal obstruction but is seldom or never found without intrinsic obstruction of the duodenum. Duodenal atresia and stenosis may be associated with other congenital anomalies, like intestinal atresia and congenital heart disease and may be part of VACTERL association. About 30 percent of the patients have Down’s syndrome.24-26 Duodenal atresia and stenosis occur with equal frequency in boys and girls. Prematurity and maternal polyhydramnios are common. Bilious vomiting in the first few hours of life is the cardinal symptom but those with duodenal stensois can present at variable times, because the clinical findings depend on the degree of stenosis. Bilious vomiting is a feature in 80 percent of neonates with duodenal atresia as the atresia is present distal to the ampulla of Vater. In the remaining 20 percent, the vomitus is non-bilious.3

Imaging Features In newborns with duodenal atresia, the abdominal radiograph is usually diagnostic. Air is present in the stomach and proximal duodenum, but there is no air distally in the gastrointestinal tract. Erect film shows two gas-fluid levels in which the higher, larger bubble to the left is the stomach and the other bubble is the dilated proximal duodenum which is seen above the region of obstruction.11 Thus, the typical appearance of a “double-bubble sign” represents air, or air and fluid filled distended stomach and duodenal bulb (Fig. 9.10). In duodenal stenosis, the stomach and duodenal bulb usually are distended, but air is present in the distal bowel. In newborns with evidence of complete duodenal obstruction on abdominal radiograph, there is mostly no need for further radiologic investigation. If enough air is not present to adequately

Duodenal Web In patients with duodenal webs, the findings on UGI vary. In some, the appearance is of complete obstruction, in others there is narrowing of the duodenum. In the latter, a web is indistinguishable from simple duodenal stenosis. The most diagnostic appearance of a web is that of a thin, convex, curvilinear defect extending for a variable distance across the lumen of the duodenum. The “wind sock” appearance that a duodenal web may have in an adult or older child, the so called intraluminal duodenal diverticulum, is not seen in newborns. This appearance is probably due to stretching and redundancy of the web caused by years of peristalsis, proximal to an incomplete obstruction.27 Annular Pancreas Annular pancreas is due to anomalous pancreatic tissue encircling the second part of duodenum. It is believed to result from the failure of normal pancreatic tissue to rotate around the duodenum. The duodenal obstruction may be total at the time of birth if a complete ring is formed. If the ring is incomplete, the obstruction may occur later in life or may never produce symptoms.11 With severe obstruction, patient presents as a neonate. Presenting symptoms with delayed presentation are usually pain and vomiting. Radiographs are normal. On upper GI studies, a persistent waist is seen, partially obstructing the second part of duodenum.3 Preduodenal Portal Vein Preduodenal portal vein is rarely the sole cause of duodenal obstruction and is rarely diagnosed preoperatively. It is thus important for the surgeon to be aware of the association of this anomaly with the other congenital lesions causing duodenal obstruction.3 A preduodenal portal vein (persistent left vitelline vein) results from normal situs asymmetry and is commonly seen in patients with heterotaxy. The resultant portal vein courses anterior to the pancreas and duodenum. The condition is diagnosed by

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Figs 9.11A and B: Barium meal follow through study shows (A) jejunal loops on the right side of the abdomen and (B) colon and cecum on the left side, with the ileum seen crossing the midline from right to left – Non-rotation

identifying the prepancreatic course of the portal vein on sonography, CT and MR imaging. It is now believed that in most cases of duodenal obstruction associated with a preduodenal portal vein, the obstruction is due to a primary, obstructing duodenal lesion such as intraluminal membrane or web and such a lesion should be suspected in these patients if duodenal obstruction is present.21

SMALL BOWEL Anomalies of Rotation and Fixation Embryology At approximately sixth week of gestation, the primitive midgut herniates into the extraembryonic coelom in the umbilical cord. The proximal and distal portions of the midgut elongate and rotate 270 degrees anticlockwise around the axis of the superior mesenteric artery. By the end of the third month of gestation, the bowel loops return to their final position in the abdominal cavity. Fixation of the duodenojejunal junction or the ligament of Treitz in left upper quadrant occurs. The cecum is the last part of the GIT to be fixed and it normally comes to lie in the right lower quadrant. When all or part of the physiological rotation of bowel fails to occur, a wide variety of anomalies of intestinal rotation and mesenteric fixation occurs which consist of nonrotation, malrotation or reversed rotation.12 i. Nonrotation – It is an asymptomatic condition in which the small bowel lies entirely on the right side and the colon on the left side. It is demonstrated incidentally on barium studies in older children or adults. (Figs 9.11A and B). The bowel is not very mobile and volvulus is not a common complication of nonrotation of the bowel.

ii. Malrotation – In malrotation of the bowel, final position of the GI tract is somewhere between normal and complete nonrotation.12 Malrotation is a general term that includes a wide spectrum of anomalies that occur when this intestinal rotation and fixation occurs in an abnormal fashion. It can also be referred to as “malfixation”. Most commonly, there is incomplete rotation, which leads to a shortened mesenteric root which may have a narrow rather than a broad base that has a tendency to twist on its axis. This leads to extrinsic compression of the bowel, causing bowel obstruction, and if the twist persists, it may lead to occlusion of the mesenteric vessels. This twist of malfixed intestines around the short mesentery is called a midgut volvulus. (Figs 9.12A to C). In patients with malfixation of the bowel, in addition to the absence of a normal mesentery, frequently there are aberrant peritoneal bands (Ladd’s bands). These bands extend from the malpositioned cecum across the duodenum and attach to the hilum of the liver, posterior peritoneum or abdominal wall and can cause extrinsic duodenal obstruction24 (Figs 9.13A & B and 9.14). iii. Reversed intestinal rotation – It is a rare rotational anomaly which renders the hepatic flexure and left transverse colon posterior in position. These portions of the colon lie behind the descending duodenum and the superior mesenteric artery. The cecum is usually malrotated and medially placed and the small bowel is more right-sided than normal. Obstructing bands and midgut volvulus can occur.12

Clinical Features Two-thirds of patients who are symptomatic present with an acute onset of bilious vomiting in the first month of life with many of them presenting in the first week of life. Fifteen to twenty percent

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Figs 9.12A to C: Illustration of midgut volvulus. Narrow mesenteric attachment of nonrotation (A) or incomplete rotation (B) may lead to midgut volvulus (C)

Figs 9.13A and B: Diagrammatic representation of Ladd’s bands causing duodenal compression in patients with malrotation. The cecum is left sided (A) and mid-line (B) in position and has dense peritoneal bands crossing over the duodenum

of patients present in late infancy or early childhood. In the remaining patients, malrotation is seen as an incidental finding. The bowel obstruction may be caused by the volvulus, by Ladd’s bands, or both. The sudden onset of bilious vomiting in a newborn who has been normal for the first few days of life should be considered to be due to a midgut volvulus until proved otherwise.

Imaging Features Plain radiographs may show feature of duodenal obstruction due to partially obstructing Ladd’s bands. The duodenal bulb dilatation

Fig. 9.14: Midgut malrotation with Ladd’s bands: Barium study shows distended proximal duodenum with tapering at the level of obstruction indicative of extrinsic compression. The small intestine, distal to the usual site of the ligament of Treitz lies below the duodenum and to the right

is less than that seen with duodenal atresia. There may be little distal bowel gas. When there is a volvulus, the plain films may show features of distal bowel obstruction. Bowel-wall thickening and pneumatosis may be present due to volvulus-induced ischemia. The fluid-filled bowel loops associated with volvulus can simulate an abdominal mass. The abdomen may be gasless, which may be due either to proximal obstruction or to diffuse

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Figs 9.15A and B: Upper GI barium study in two different patients showing classic “corkscrew” appearance of the duodenum in midgut volvulus

bowel necrosis in midgut volvulus. Of all the congenital anomalies that result in bilious emesis, only malrotation is likely to produce a normal abdominal film.24 Upper gastrointestinal barium examination is performed to document the location of ligament of Treitz and to evaluate for duodenal obstruction. Normally, the duodenojejunal junction lies to the left of the body of the first or second lumbar vertebra at the level of the duodenal bulb. In malrotation, it is located lower and to the right of normal. It is important to remember that the duodenojejunal junction is mobile in children and may be pushed inferomedially by an overdistended stomach, chronic bowel dilatation, enlarged spleen or in the presence of a nasojejunal tube. 3 A lateral view of the contrast filled duodenum is an important additional view in the upper GI study when evaluating for malrotation. Normal duodenum being a retroperitoneal structure, on lateral views is seen to lie behind the level of the stomach, with the fourth part of the duodenum superimposed on the second part of duodenum. This superimposed relationship is lost in case of malrotation of duodenum as it is seen to course anteriorly. An abnormal position of the duodenojejunal flexure may be the only indication of malrotation, as in 16% of cases cecum occupies its normal position. In addition, in malrotation the jejunum is usually on the right side of the abdomen. However, this should not be taken as an indication of malrotation as the jejunum in a normal child is relatively mobile and may be seen to the right of the spine.3 When volvulus occurs, there may be complete or partial duodenal obstruction. With complete obstruction, a beaked tapering of the obstructed duodenum may be seen. More commonly, the volvulus is intermittent with incomplete bowel obstruction with contrast filling the proximal small bowel. Occasionally, the pathognomonic corkscrew pattern of the twisted duodenum and jejunum is seen due to their clockwise twisting around the superior mesenteric artery (Figs 9.15A and B). In

malrotation, the cecum and right colon may have abnormal mobility. The cecum is in the right upper quadrant or in midline in malrotation. A colonic beak may be present in the right colon on barium enema in the presence of volvulus.24 In the past, a contrast enema was the first investigation performed to evaluate for malrotation.3 This has been replaced by an upper GI study due to its greater sensitivity and specificity for malrotation. The cecum may be mobile in neonates and may be seen in the right upper quadrant in the absence of malrotation. A barium meal upper GI study should be done for suspected malrotation since a normal barium enema does not exclude malrotation. The position of the cecum may be normal in a significant number of patients with malrotation.21 Hence, the upper GI study is the investigation of choice for the diagnosis of malrotation. Ultrasound may be useful in the early detection of midgut malrotation as well as complicating midgut volvulus. A distended proximal duodenum with a tapered end in front of the spine is consistent with malrotation in the proper clinical set-up. If in addition, one finds peritoneal fluid and edematous bowel loops on the right, the diagnosis of volvulus can be made. A normal anatomical relationship, however, in no way excludes the possibility of malrotation. A UGI series is mandatory if this diagnosis must be confirmed or excluded prior to surgery. Ultrasound and CT scan may be helpful in suggesting the diagnosis of malrotation owing to abnormal superior mesenteric artery (SMA) or superior mesenteric vein (SMV) anatomy. The SMV normally rests to the right and anterior to the SMA. When the SMV is to the left of the SMA, this is highly suggestive of volvulus. When the SMV is anterior to the SMA, this is suggestive of malrotation with possible volvulus. Color Doppler US demonstrates ‘whirlpool’ sign due to clockwise spiralling of the mesentery and superior mesenteric vein around the superior mesenteric artery. Inversion of the mesenteric vessels or the SMV

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Clinical Features Antenatal diagnosis of small bowel atresia may be suggested on ultrasound by the presence of polyhydramnios and dilated fluid filled bowel loops. These findings are non-specific and the diagnosis is usually not confirmed until after birth.3 Proximal atresia may present with bilious vomiting; whereas more distal atresias present with abdominal distention. There may be failure to pass meconium. It is commonly associated with prematurity. Meconium may be passed if atresia is located in the jejunum or occurred later in intrauterine life.

Fig. 9.16: Axial CECT of the abdomen showing characteristic “whirlpool” sign of clockwise twisting of the SMV and mesentery around the SMA

rotation sign is not a sensitive screening test, because it may be present in normal population, patients with situs inversus and patients with abdominal masses. Other CT findings of midgut malrotation complicated by midgut volvulus are: (1) the `whirl’ sign of small-bowel loops revolved around the SMA; (Fig. 9.16) (2) a dilated, fluid-filled, obstructed stomach and proximal duodenum; (3) thick-walled loops of ischemic right-sided small bowel loops with potential pneumatosis intestinalis and mesenteric edema; and (4) free intraperitoneal fluid.

Jejunoileal Atresia and Stenosis Small bowel atresias (i.e. jejunal, jejunoileal or ileal) are more common than duodenal or colonic atresia. They are more common in the proximal jejunum and distal ileum than in the intervening small intestine.24 Jejunal atresias comprise around 50 percent of small bowel atresias and may be associated with other jejunal and ileal atresias.2 Embryology Most jejunal and ileal atresias and stenoses, except those that are familial, are thought to be secondary to ischemic injury to the developing gut. The ischemia may be due to primary vascular accident, usually in the mid second trimester or secondarily to a mechanical obstruction, as may occur in case of an in utero volvulus.24 There is no solid core phase in the development of jejunum and ileum, so recanalization is not thought to be involved. Jejunoileal atresia may involve the bowel anywhere from the ligament of Treitz to the ileocecal valve with the majority of cases of atresia occurring at the extremes of the small bowel. The devascularized bowel becomes necrotic and is resorbed leaving an atretic area of varying length with its attached mesentery. Several forms of atresia have been described surgically, but it is not possible to differentiate them by imaging studies.4

Classification Small bowel atresia usually occurs as an isolated anomaly of the gastrointestinal tract. There are four types of small bowel atresia3 (Figs 9.17A to D): Type 1—Membranous or web-like atresia, composed of mucosal and submucosal elements with no interruption of the muscularis. Type 2—Atresia with a solid fibrous cord connecting the atretic bowel ends, but the mesentery is intact. All the three layers of the intestinal wall are interrupted. Type 3—Complete absence of a segment of bowel (total atresia) as well as a portion of the mesentery (V-shaped defect in the mesentry) Type 4—The familial form of multiple atresias There are two unusual forms of atresia that are inherited.24 They are: i. “Apple peel” or “Christmas tree” atresia ii. A syndrome of multiple intestinal atresias “Apple peel” or “Christmas tree” atresia is a rare variant of Type 3 atresia which consists of proximal jejunal atresia with absence of the distal superior mesenteric artery, shortening of the small bowel distal to the atresia and absence of the dorsal mesentery. This type of atresia is probably caused by prenatal occlusion of the SMA, distal to the origin of the midcolic artery. The distal small intestine spirals around its vascular supply giving the characteristic apple peel appearance (Fig. 9.17D). The result is a very short intestine with a propensity towards necrotizing enterocolitis.28 The syndrome of multiple intestinal atresias with intraluminal calcification is transmitted as an autosomal recessive pattern. There are multiple atresias from stomach to rectum. The radiological hallmark of this syndrome is extensive calcification of intraluminal contents between the areas of atresia. Nonhereditary bowel atresias may also demonstrate intraluminal calcification.24 Imaging Features Plain radiograph of the abdomen demonstrates typical findings of small-bowel obstruction. The site (jejunal or distal ileal) of the atresia can be suspected by the number and location of gas-filled loops of bowel.3 (Fig. 9.18). Proximal jejunal atresia may have a few markedly dilated loops, the so-called triple bubble sign, more distal atresia typically has a more uniform dilatation of small bowel with associated air-fluid levels. The loop just proximal to the site of atresia is frequently disproportionately distended, with

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Fig. 9.17: Types of small bowel atresia

Fig. 9.18: Small bowel atresia. Air is seen in the stomach and dilated part of the jejunum proximal to the atresia

Fig. 9.19: Plain radiograph of the abdomen in a case of meconium peritonitis shows curvilinear calcification in the right flank

a bulbous end. If the ischemic event that produced the atresia caused a perforation, there may be evidence of meconium peritonitis which is a chemical peritonitis occurring as a result of extruded bowel contents producing an intense peritoneal inflammatory reaction. It leads to the formation of dense fibrotic tissue which often calcifies, resulting in characteristic intraperitoneal calcifications. Peritoneal calcifications may be identified on plain films as a consequence of meconium peritonitis, wherein they are seen as linear or flocculent areas of calcification within the peritoneal cavity. (Fig. 9.19) The most frequent finding is a linear calcification under the free edge of

the liver, though any or all portions of the peritoneum may be involved.4 The calcification may extend into the scrotum through a patent vaginal process to produce a calcified mass in the scrotum.28 The association of meconium peritonitis with small bowel obstruction is virtually diagnostic of small bowel atresia.4 Ultrasound depicts the calcifications of meconium peritonitis as highly echogenic linear or clumped foci in the abdomen or pelvis. The appearance of meconium peritonitis on US may be either generalized or cystic. In the generalized condition, highly echogenic material spreads throughout the abdomen and around the bowel loops to produce a characteristic “snowstorm”

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a normal colon does not exclude it in all cases. Also, microcolon on contrast enemas may be seen in premature infants and occasionally, in total colonic aganglionosis (long segment Hirschsprung’s disease). The rectum is distensible in distal ileal atresia, thereby distinguishing it from the microcolon of long segment Hirschsprung’s disease.3 Jejunal atresia does not lead to a microcolon because the remaining small bowel, distal to the atresia produces sufficient succus entericus to give a colon of normal caliber. Hence, a microcolon in the presence of a high bowel obstruction indicates a second, more distal atresia.3 Surgical treatment involves resection of the atretic portion of the intestine with reanastomosis. The proximal dilated bowel may remain dilated for sometime in the post operative period, showing delayed motility with delayed passage of contrast across a widely patent anastomosis.

Fig. 9.20: Small bowel atresia. Contrast enema demonstrates a microcolon

appearance. Encysted collections of meconium show a variable appearance from homogeneous to heterogeneous echogenicity and may be ill-defined or well defined. Sonography may also be useful in differentiating ileal atresia from meconium ileus. In ileal atresia, the bowel contents are echopoor while in meconium ileus, the dilated bowel loops are filled with echogenic material.21 Additional imaging is not required in the presence of a high intestinal obstruction. A contrast enema is required for further evaluation for low bowel obstruction to distinguish between a large or distal small bowel obstruction, as the differentiation of the two on plain radiographs may be difficult or impossible. The most common causes of neonatal distal small bowel obstruction are ileal atresia and meconium ileus.3 Contrast enema should be performed with water soluble low osmolar contrast media introduced via a soft rectal catheter. Care must be taken to perform the enema as the distal blind pouch is prone to perforation. The one diagnostic finding to be looked for in the contrast enema performed in a setting of low bowel obstruction, is the presence or absence of a microcolon (Fig. 9.20). A microcolon is a colon of very small caliber, generally less than 1cm diameter, and the entire colon must be involved. (i.e. not a portion as in small left colon syndrome). Normally, colonic measurements are not needed for diagnosing microcolon as it is usually obvious on inspection. The colon is small owing to lack of use rather than anatomic or functional abnormality. The more distal the small bowel obstruction, the smaller the colon. A microcolon or unused colon occurs when no or little intestinal juices (succus entericus) reaches the colon and is highly suggestive of a distal small bowel obstruction (meconium ileus or ileal atresia). A normal sized colon almost always excludes these diagnoses.24 It is important to remember that the presence of microcolon is diagnostic of long standing distal small bowel obstruction, but

Meconium Ileus Meconium ileus is a low intestinal obstruction caused by inspissation of abnormal meconium in the distal ileum.24 It is almost always associated with cystic fibrosis and is a presenting feature of cystic fibrosis in 5 to 10 percent of these patients.24 The lack of normal pancreatic enzymes leads to thick, tenacious meconium that collects in the distal ileum and cecum, occluding its lumen and resulting in high grade distal small bowel obstruction. Meconium ileus can be complicated or uncomplicated, with complicated meconium ileus being seen in up to half of the patients which include intestinal atresia, volvulus of the distal intestinal loop and perforation with meconium or pseudocyst formation.3 Imaging Features Meconium ileus is the most common mimic of small bowel atresia clinically and on plain films.4 Plain radiograph may demonstrate a distal bowel obstructive pattern with air-fluid levels. Bowel loops may vary in size, a finding seen less often in atresia. The dilated small-bowel loops that contain air can mimic colon loops in size and course. In addition, some air mixes with the viscid meconium and results in a bubbly appearance in the right lower quadrant. This “soap bubble appearance” is not specific and a similar fecal pattern can be seen with any cause of distal intestinal obstruction like ileal atresia, colonic atresia, aganglionosis of the terminal ileum and meconium plug syndrome.28 Patients with meconium ileus have fewer air-fluid levels than patients with small-bowel atresias. Meconium peritonitis may occur and be associated with peritoneal calcifications. However, this differential point is not specific in all cases. A localized perforation forms a meconium pseudocyst which may have peripheral curvilinear calcifications seen on plain radiographs. The term pseudocyst is also used to refer for a mass of necrotic, fluid-filled bowel loops with a fibrous wall which may be seen as a mass on radiographs.3 Ultrasound can detect abnormal bowel dilatation and echogenic bowel contents in infants with meconium ileus. Ultrasound can also pick up complications of meconium peritonitis or pseudocyst which is seen as echogenic material lying outside the bowel loops, with or without associated calcification.

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Upper GI contrast study shows hypomotility of small bowel with retrograde peristalsis. Ultrasound reveals a dilated bladder with bilateral hydroureteronephrosis.21 The prognosis is poor for longterm survival.

Fig. 9.21: Meconium ileus: Water soluble contrast enema showing a microcolon. Filling defects due to meconium are seen in colon and distal ileum

The colon of babies with meconium ileus is often said to be the smallest of all colons, and is empty except for a few occasional pellets of meconium. The distal 10 to 30 cm of ileum appears dilated due to meconium within and may even displace the right colon to the left.24 Definitive diagnosis is made with a low osmolal water soluble contrast enema which demonstrates a microcolon with inspissated meconium pellets identified in the collapsed distal ileum with dilated small bowel proximal to the obstruction (Fig. 9.21). Uncomplicated cases of meconium ileus may be treated with multiple contrast enemas, i.e. one or two enemas per day. The aim is to introduce the contrast into the dilated small bowel, proximal to the obstructing inspissated meconium. But care must be taken not to overdistend the meconium. This leads to mechanical loosening of the meconium pellets. The patient should be well hydrated if high osmolarity agents are used because of fluid shifts. The therapy is largely mechanical and the osmotic load probably plays little role. Repeated enemas may be used only if progress is seen in decreasing the obstructing pellets. In premature infants, isotonic non-ionic contrast medium is used. Enema has a success rate of about 50 to 60 percent in treating meconium ileus.3 If signs of obstruction are not relieved or perforation/peritornitis develop, further attempts at therapeutic enema should be abandoned. Surgery in such patients often reveals complicated meconium ileus.

Megacystis-microcolon-intestinal Hypoperistalsis Syndrome (Berdon Syndrome) Megacystis-microcolon-intestinal hypoperistalsis syndrome is a pseudoatresia. There is a functional small bowel obstruction with a microcolon, malrotation and a large unobstructed bladder. There is four-to-one female predominance with associated genitourinary and congenital heart malformation in up to 14 percent cases.

Meckel’s Diverticulum Meckel’s diverticulum is a congenital blind pouch in the small bowel which results from an incomplete obliteration of the proximal part of the vitelline duct (omphalomesenteric duct) during the fifth week of gestation. It results in a true diverticulum arising from the antimesenteric border of the distal ileum.29 For Meckel’s diverticulum, the common rule by which it is known is the “rule of twos,” i.e.–it is found in 2 percent of the population, twice as common in males, most frequently found in those less than 2 years of age and usually 2ft from the ileocecal valve. It may contain ectopic mucosa, usually gastric mucosa which is responsible for the adjacent ulceration in the ileum. Meckel’s diverticulum usually does not give rise to symptoms. Bleeding is the most common complication in children reported in over 50% of cases, while it is seen in only around 12% cases in adults. Bleeding is usually minor, resulting in chronic anemia.22 It may present with malena due to ulceration of ectopic gastric mucosa in its wall. In 20-30 percent of patients, it may give rise to symptoms such as inflammation, and or perforation which may often be indistinguishable from acute appendicitis. Obstructive symptoms have been seen to occur more frequently than hemorrhage in patients with Meckel’s diverticulum presenting in adulhood. The obstruction may occur due to intussusception, volvulus, inflammatory adhesions. The diverticulum may get obstructed with resulting diverticulitis, may present as a mass and initiate intussusception in childhood. Preoperative evaluation of a Meckel’s diverticulum is difficult, and routine and special radiological studies such as plain abdominal radiograph, barium meal follow through, arteriography and computed tomography are often non-diagnostic and often of limited diagnostic value. The diverticulum is seldom recognized on a small bowel follow-through study because there is no significant hold-up, and the barium residue remaining in it is very small because of its wide neck.29,30 In suspected symptomatic Meckel’s diverticulum, preoperative evaluation includes 99mTc (technetium -99m pertechnetate) scanning which relies on the presence of ectopic gastric mucosa. In this study, 99mTc is injected intravenously, and over time it accumulates in the gastric mucosa. As symptoms such as bleeding is caused by the ectopic gastric issue, 99mTc scanning may help in the diagnosis in symptomatic cases. In children, the scan has a sensitivity of 85 percent and specificity of 95 percent, but in adults the sensitivity is 62.5 percent and the specificity 9 percent. The accuracy of the scan can be improved with the use of pentagastrin or cimetidine. In patients with non diagnostic scan or with nonbleeding presentation, ultrasonography could prove to be useful in achieving a diagnosis. Enteric Duplication Gastrointestinal duplications are uncommon congenital abnormalities that may occur anywhere in the gastrointestinal tract. But the most common locations are the distal ileum (35%),

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Figs 9.22A and B: Esophageal duplication – chest PA showing a well-defined soft tissue mass in the left hemithorax (A) lying posteriorl in the lateral film (B). There is associated hyperinflation of the let lung. The vertebral bodies appear normal

distal esophagus (20%) and stomach (9%) followed by duodenum and jejunum. Colonic and rectal duplications are rare. Multiple duplications may be present in 15-20% cases. 21 Enteric duplication occurs in the late first or early second trimester owing to abnormal canalization of the bowel. The duplication has smooth muscle in its wall with gastrointestinal mucosal lining. The wall thickness is 3 to 5 mm as seen in normal bowel. It is usually adjacent to and in most instances, does not communicate with the gastrointestinal tract. In most cases of hemorrhage or ulceration, gastric mucosa is present. Esophageal duplications are located at the posterior aspect of the esophagus. Gastric duplication is found along the greater curvature of the stomach interposed between the stomach and the transverse colon. Duplications may be spherical or tubular. Tubular duplication is more likely to communicate with the adjacent bowel. They typically occur along the mesenteric border of the intestine and share a common blood supply. Thus the tubular type of duplication may complicate bowel-sparing surgery because of difficulty in preserving the enteric blood supply. Unlike neurenteric cysts, duplication cysts are usually not associated with vertebral segmental anomalies.29

Clinical Features Duplications can present with a variety of symptoms and signs depending on the site of duplication and its size. Upper esophageal duplications present with symptoms due to tracheal compression. Other symptoms include nausea and vomiting. In the presence of heterotopic gastric mucosa, patients may present with gastrointestinal hemorrhage or even perforation. Patient may also present with distention, ulceration, volvulus, an abdominal mass lesion or with obstruction, particularly when the duplication is in the region of the ileocecal valve or duodenum. Forty percent of patients with enteric duplication present by one month of age, with 85 percent diagnosed during the first year of life.

Malrotation, genitourinary anomalies and jejunal or ileal atresias are also seen. Duplications are more common in boys except for gastric ones, which occur without gender predominance.

Imaging Features Plain radiographs may demonstrate a mass lesion, especially in the chest in the case of esophageal duplication, (Figs 9.22A and B). The bowel gas pattern may suggest an obstruction, particularly with duodenal or ileal duplications. Enteric duplication cysts may reveal mural calcifications. Occasionally, duplication may get filled with barium suspension during gastrointestinal examinations. In most cases, however, the duplications are not demonstrated in this manner. Barium study usually reveals extrinsic compression (Figs 9.23A and B) of the bowel or an obstruction. On ultrasonography, a duplication cyst appears as a welldefined, unilocular anechoic mass with good through transmission (Fig. 9.24). Rarely the contents are reflective or contain septations secondary to hemorrhage or inspissated material within the lumen. A highly reflective mucosa and a surrounding echo poor muscular wall may be seen as the duplication is of gastrointestinal origin.31,32 This is most easily identified in the dependent portion of the cyst.21 The presence of this double layered appearance (“gut wall signature”) is relatively specific for the diagnosis of duplication cyst and is useful to exclude other cystic masses, such as mesenteric or omental cyst, choledochal cyst, ovarian cyst, pancreatic pseudocyst or abscess. The reflective lining may be absent as a result of extensive mucosal ulceration by gastric enzymes. Radionuclide studies may be useful in 30 percent of patients where the enteric duplications have gastric mucosa. Free pertechnetate is taken up and secreted by gastric mucosa, thus localizing the enteric duplication.5

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Figs 9.23A and B: Barium study shows extrinsic impression on the body of the stomach with effacement of the mucosa in AP and lateral views in a case of gastric duplication

atresia, and with a functional element, aganglionosis or Hirschsprung’s disease. A group of poorly understood disorders like meconium plug, neonatal small left colon syndrome, etc. cause transient self-limited functional obstruction.

Fig. 9.24: Ultrasound abdomen reveals a well-defined, smooth rounded cystic lesion with inner echogenic mucosal stripe and outer hypoechoic muscle layer–Enteric duplication

CT or MRI may be useful in further characterizing the nature of enteric duplication cysts when the diagnosis is unclear, wherein they are seen as well-marginated, smooth walled masses of fluid attenuation/signal not showing any contrast enhancement. (Figs 9.25A and B).

LARGE BOWEL Colonic Obstruction Obstruction of the colon in the newborn may be either anatomical or functional. The first type includes atresia of the colon, anorectal

Colonic Atresia Colonic atresia is quite rare as compared to atresias of the small bowel.24 It is thought to be secondary to vascular insult. Multiple atresia syndromes may involve the colon in addition to small bowel. Proximal location is more common than distal, with atresias beyond the splenic flexure being unusual. If atresia is located in the ascending colon, it may often be indistinguishable from obstruction of the distal ileum.28 The classification system based on the anatomic appearance is same as with jejunoileal atresia. Type I represents a diaphragmatic occlusion, type II represents a complete atresia with a blind, solid cord extending between the two ends of atretic segment; and type III represents a complete atresia with complete separation and an associated Vshaped mesenteric defect. Clinical Features Patients present with distension and failure to pass meconium. Presentation may be delayed up to 48 hours, if the atresia is proximal. Imaging Features Prenatal sonography may demonstrate dilatation of the colon proximal to the atresia. Plain radiograph may demonstrate a distal obstruction with multiple air-fluid levels and may be nonspecific. Occasionally, a hugely and disproportionately dilated loop of bowel may be present and render the plain film evaluation highly suggestive of the diagnosis.2 A “soap-bubble” appearance of retained meconium

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Figs 9.25A and B: CECT images of esophageal and gastric duplications of the two patients of the same case as in Figures 9.22 and 9.23 show sharply marginated, non-enhancing, homogeneous mass of water attenuation in the (A) posterior mediastinum and (B) along the greater curvature of stomach.

may be seen. There is dilatation of the proximal colon up to the level of the atresia, unless multiple atresias are present. Contrast enema shows a microcolon, distal to the atresia with obstruction to the retrograde flow of barium at the site of atresia. The colon may have a hook or question-mark appearance at the site of atresia. The colon is often non-fixed or malpositioned in the midline. The distal colon segment may perforate into the peritoneal cavity during a contrast enema because often the blind end is covered with only mucosa.

Hirschsprung’s Disease (Aganglionosis of the colon) Hirschsprung’s disease is a condition caused by absence of normal ganglion cells in a segment of the colon, leading to a form of low intestinal obstruction. It accounts for around 15-20 percent of cases of neonatal bowel obstruction.28 Embryology In normal intrauterine development, neuroenteric cells migrate from the neural crest to the upper end of the gastrointestinal tract by 5 weeks and then proceeds in a caudal direction. These cells reach the rectum by 12 weeks and commence the intramural migration from Auerbach’s (myenteric) plexus to the submucosal plexus. Hirschsprung’s disease is caused by abnormal neural crest cell migration, resulting in arrested distal migration of these cells.3 As the normal migration is continuous from proximal to distal, the part of the GI tract distal to the site of arrest is aganglionic.8 In the majority of cases (75-80%), the aganglionic segment is limited to the rectosigmoid region (short segment aganglionosis). The aganglionosis always involves the anus and internal sphincter and extends proximally for a variable distance. The transition from innervated to aganglionic bowel is found in the rectosigmoid region in 73 percent of patients, the descending colon in 14%, and more proximal colon in 10 percent, according to Swenson et al.8 Total colon aganglionosis involves the entire

colon and part of the terminal ileum. It can very rarely involve the large as well as whole of the small bowel, which is incompatible with life. At the other end of the spectrum is ultrashort segment Hirschsprung’s disease which is also rare. In this type, the aganglionosis is limited to the region of the internal sphincter.3 The ultrashort segment can only be diagnosed by manometry (not biopsy or imaging) and is usually not diagnosed in the neonatal period.4 Skip lesions in Hirschsprung’s disease are believed to be unlikely to exist if one accepts the concept of neuronal migration down the GI tract. It is likely that such areas represent areas of intrauterine ischemic insult leading to destruction of ganglion cells.12 However, according to recently published literature, skip lesions in Hirschsprung’s disease, though a controvertial condition, is a definite entity, with 24 cases reported till date. Skip lesions have been found to occur predominantly in patients with total colonic aganglionosis (92%). The presence of a skip area of normally innervated colon in total colonic aganglionosis may influence the surgical management, enabling the surgeons to preserve and use the ganglionated skip area during pull through operations.33 Hirschsprung’s disease may be associated with certain congenital anomalies like intestinal atresia, malrotation. Down’s syndrome is present in 2-3 percent cases.

Clinical Features The absence of ganglion cells interrupts the normal propagation of colonic peristalsis. Patients with Hirschsprung’s disease fail to pass meconium in the first 48 hours of life. They may present with abdominal distention, bilious vomiting, or enterocolitis. Over 80 percent of patients present within the first 6 weeks in life. Hirschsprung’s disease is about three to four times as common in boys as in girls. Older children may present with chronic constipation. Hirschsprung’s disease can be complicated by life threatening enterocolitis which presents with diarrhea, abdominal distention and fever and may progress to perforation with peritonitis.3

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Fig. 9.26: Plain X-ray abdomen showing a dilated proximal sigmoid colon with a smaller distal sigmoid with relatively little rectal gas in a neonate with Hirschsprung’s disease

Fig. 9.27: Hirschsprung’s disease: Barium enema shows an abrupt transition from the narrow caliber rectosigmoid (aganglionic) to the larger caliber more proximal sigmoid colon

Imaging Features Plain films may demonstrate features of distal bowel obstruction. However, a dilated colon proximal to the distal and smaller aganglionic segment is the more typical finding (Fig. 9.26). A small gas-filled rectum can be seen, especially on prone films and may help in the diagnosis. The absence of rectal gas is not specific for Hirschsprung’s disease as it is commonly seen in infants with sepsis and necrotizing enterocolitis.21 At times, the bowel pattern may appear normal. Less commonly (4%), pneumoperitoneum

may be seen in patients with long segment or total colonic disease secondary to colonic perforation. The radiographic diagnosis is made by contrast enema and is directed towards identifying the transition zone which is the most specific sign of Hirschsprung’s disease. This is where the normalsized, distal aganglionic bowel changes in caliber to join the proximal ganglionic bowel.3 This findings may not be obvious in the newborn, hence, careful attention should be given to the technique of performing barium enema. Barium enema is performed on an unprepared patient by inserting a straight-tipped catheter to a point just beyond the anal sphincter. Balloon catheters are not used to avoid expanding a narrow segment of aganglionic colon, and may thus obscure the diagnosis. There is also risk of perforation of the stiff aganglionic rectum.24 Barium contrast should be prepared with normal saline to avoid possibility of water absorption from the large surface area of dilated colon.29 With the patient in the lateral position, barium suspension is introduced slowly by gravity drip infusion, under fluoroscopic monitoring. The infusion is stopped and restarted as serial spot radiographs are obtained. As filling progresses into the descending colon, the patient is rolled into the supine position. If the examination is positive, the diagnosis in most cases is made by the time the barium fills the proximal descending colon. Rapid infusion of barium suspension can distend and mask the transition zone. When the transition zone is observed, the examination should be discontinued because filling of the more proximal dialated bowel beyond the transition zone may lead to impaction. However, the distention of the bowel, proximal to the aganglionic segent is gradual, and a transition zone is seen in only 50% of neonates during the first week of life.28 The transition zone generally is funnel-shaped and it is an important diagnostic feature. In some instances, the transformation from dilated bowel to narrowed bowel is abrupt (Fig. 9.27). In other cases, the funneling of the bowel occurs incrementally over a long segment of bowel to appear almost imperceptible because of the gradual change in caliber. In long segment Hirschsprung’s disease, a variable portion of the colon proximal to the sigmoid colon is aganglionic (Fig. 9.28). The pathological transition zone is usually somewhat more proximal than the radiographical one. Under fluoroscopic visualization, irregular saw-toothed mucosal pattern may be seen due to disordered contractions in the aganglionic colon (Fig. 9.29). Another radiographic appearance of Hirschsprung’s disease that has been described in neonates and young infants in whom the rectosigmoid region appears normal, is the presence of straight transverse bands in the involved segment of colon. These bands are thought to represent areas of persistent spasm.12 The rectosigmoid index can be used in the diagnosis of Hirschsprung’s disease confined to the rectum. This compares the ratio of the rectal diameter to the sigmoid diameter and is considered abnormal if the sigmoid colon is more dilated than the rectum (R/S index 3 mon) c. Concentric position d. Subluxation

50°-60°

77°

— Labrum everted

Evaluation by orthopedic surgeon Required

III

Low dislocation

70°

cartilaginous acetabular rim. A large β angle indicates lateral migration of femoral head. Classification of hip types on ultrasound studies is given in Table 22.1. Calculation of α and β angles is not possible if the femoral head is dislocated in anterior or posterior direction. Graf described type I and II a/b as inherently stable and types II d, III and IV as inherently unstable and found that it is only necessary to test for stability with type IIc (Figs 22.20 and 22.21). Coronal images are also used to evaluate the position of the femoral head within the acetabulum. If the acetabular cup accommodates less than one-third of the femoral head, than acetabular dysplasia is definitely present and must be suspected, if only half to one-third is accommodated (Fig. 22.22). Harcke and Grisson 14 advocate the use of dynamic sonography of the infant hip, based on the premise that the position and stability of the femoral head are key factors in the diagnosis and management of DDH. If the femoral head is

properly positioned and stability is achieved, then acetabular development will proceed. The US examination is modeled after clinical examination and based on provocative tests for dislocating the unstable hip and the reduction of the dislocated hip. The standard US examination should consist of two particular views: Transverse neutral and coronal-flexion (Fig. 22.23). The value of the coronal flexion view is that it reflects the position in which the physician places the hips during the dynamic physical examination. The ossific nucleus is graded for size (0= no center present, 1= center size 0.5 cm but acetabulum visible; 3= center size large enough to prevent visualization) (Fig. 22.23). In the transverse plane, with the infant’s hip flexed, the hypoechoic cartilaginous femoral head is viewed between two echogenic limbs of a ‘V’ (in adduction) or U (in abduction). Stability can also be assessed in the coronal plane while pistoning the hip anteroposteriorly (knees flexed), (Fig. 22.24).

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Fig. 22.20: USG—Gross superolateral hip dislocation with complete disruption in alignment with the acetabulum (Type IV CDH)

Fig. 22.22: USG—62 percent coverage of the femoral head within the acetabular cup

Fig. 22.21: USG old neglected CDH on the right with normal left hip

Rosendahl and co workers in 1992 described a modified Graf’s method classifying hip morphology and hip stability separately. Hip morphology (alpha angle) was assessed using the standard coronal view with the femoral head centered. In cases of decentered or dislocated hips-Graf type 2c, D, 3, 4a, the femoral head was relocated by mild traction on the thigh before morphology could be studied. A Barlow maneuver was applied to assess a coexisting instability. A technique for assessing the degree of lateralization of the femoral head on the basis of Harcke’s coronal flexion view was proposed by Morin et al. in 1985. Based on two lines paralleling Graf’s baseline, one tangent to the lateral part of the femoral head and one tangent to the medial junction of the head and acetabular fossa were drawn, they measured distance between medial and iliac lines (d) and between the medial and lateral lines (D). The ratio of d to D multiplied by 100 indicated the percentage of the femoral head covered by the bony acetabulum.15 Pediatric radiologists are relying increasingly on the use of dynamic sonography as this allows real time observation of

Fig. 22.23: Schematic diagram of Harcke’s dynamic four step method. (A) Transverse neutral view (B) Transverse flexion view (C) Coronal flexion view (D) Coronal neutral view. Ant – Anterior, Lat – Lateral, P – Pubis, I - Ischium A = Femoral head, T – Triradiate carlitage, M – Femoral metaphysis, IL. Ilium.

Chapter 22 ™ Imaging of Pediatric Hip 361

Fig. 22.24: USG—hip flexed transverse plane—femoral head viewed between two echogenic limbs of pubis and ischium in adduction (‘V’)

maneuvers allowing a more accurate depiction of the femoral head in relation to the acetabulum as the hip position is changed. Hence, it allows not only depiction of DDH but is also able to assess whether a particular closed reduction is appropriate. Sonography can also be used to monitor treatment of patients with DDH in a spica cast, brace or Pavlik harness. The long axis anterior approach may be useful in a patient with a spica cast in which a window cannot be cut for lateral scanning. The window should be repositioned and the cast repaired to avoid posterior hip dislocation. The sonographic follow-up of patients being treated in a Pavlik harness is however easy as it permits movement within a safe zone while the degree of restriction prevents subluxation or dislocation. Improvement should be seen within 3 weeks of treatment. Duplex Doppler US has been used to assess vascularity of the femoral head in an infant undergoing abduction treatment. The normal spectral waveform of arterioles in the femoral head of an infant is a slow flow, low resistance arterial pattern with resistive indices ranging from 0.2 to 0.68 (mean 0.48 ± 0.11).16 Power Doppler can be used to visualize blood flow in the cartilaginous femoral head to ensure that flow is not compromised during treatment.

CT CT is useful for the evaluation of concentricity of closed reduction, detection of iliopsoas muscle deformity or intraarticular soft tissue obstacles such as hypertrophied fibrofatty pulvinar which can make it difficult to achieve concentric reduction by the closed method, for detection when the surgical procedures are to be performed and for the determination of femoral torsion and acetabular configuration. It can be performed even when the patient is casted (Figs 22.25A & B and 22.26). CT is most useful in postoperative assessment of reduction. Injection of contrast medium into joint is often performed during intraoperative reduction. CT done soon after allows the

Figs 22.25A and B: CT-MPR (A) and VRT (B) shows right femoral epiphysis dislocated superiorly and posteriorly (For color version Fig. 22.25B see plate 8)

contrast medium surrounding the nonossified femoral head to be identified. This helps in assessment of the alignment of the femoral head and its relationship to the acetabulum. The use of three-dimensional imaging allows direct assessment of the amount of anterior and posterior acetabular coverage. Standard CT protocols allow images to be obtained in the standard frog leg position. Even though the femoral head may not be ossified the position of the femoral metaphysis relative to the midportion of acetabulum can be evaluated. CT scanning allows differentiation of lateral from posterior hip dislocations. Lateral displacement shows the labrum and capsule unfolded secondary to a tight iliopsoas tendon. In posterior dislocation approximation of the femoral metaphysis and acetabulum, projection of a mass behind the ischium and posterior displacement of pregluteal fat plane is seen. Acetabular

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Fig. 22.26: CT case of DDH with hip spica

anteversion is measured by determining the angle of the anterior and posterior rim relative to the vertical axis of the pelvis (Figs 22.27A and B). Increased acetabular anteversion has been noted in dysplastic hips and also in some healthy volunteers. Acetabular sector angles are more specific to the presence of hip dysplasia (Figs 22.28A and B). Anterior and posterior sector angles reflect the degree of anterior and posterior acetabular support.17 The sector angles are determined by measurement of the angle drawn between the center of the femoral head and the anterior and posterior acetabular rim relative to the horizontal axis of the pelvis. A normal anterior angle is greater than 50° and a normal posterior angle is greater than 90°. These angles are reduced in developmental dysplasia, which reflects acetabular support. Measurements of acetabular angles, have however not been found predictive of the outcome of DDH.18

MR MR is used in the evaluation of dysplasia of the hip when there is (i) a complex dysplasia, (ii) there has been inadequate response to treatment, (iii) in late presentation and (iv) teratological dislocation. Axial and coronal MR images are most useful and small surface coils with high spatial resolution are necessary to evaluate DDH. The value of MR imaging in preoperative planning is due to its ability to portray the cartilaginous part of the pelvis and also analyze the relationship of the femoral head to the acetabulum and labrum. The femoral head is variably laterally displaced in DDH, with posterior and superior reduction. MR shows femoral head coverage in both coronal and axial planes without need for complex radiographic projections or magnification correction. The degree of coverage by the cartilaginous acetabulum and labrum can be evaluated by MR. MR imaging can show changes in the shape of the acetabulum, not demonstrated on CT sonography or radiography. In DDH, the acetabulum becomes elongated

Figs 22.27A and B: Schematic diagram (A) and CT (B). Measurement of femoral anteversion from an axial CT slice. H = Horizontal line through femoral head center, P = Posterior margin of acetabulum, A = Anterior margin of acetabulum, V = Line perpendicular to line H through point PAC, AV = angle of anteversion

posteriorly or superiorly. The rim of the acetabulum becomes oval and the acetabular cartilage becomes thickened and may become displaced.19 Any obstruction to the reduction can be visualized, especially in cases where there is a history of failed closed reduction these include a flipped labrum, prominent pulvinar and a redundant ligamentum teres;capsule or illiopsoas tendon or transverse acetabular ligament, which may be interposed into the joint (Figs 22.29A and B). Prominent pulvinar is visualized as fibro fatty material in the joint, which does not allow normal seating of the femoral head within the joint. There can be a small amount of pulvinar normally present with the head being slightly laterally

Chapter 22 ™ Imaging of Pediatric Hip 363

Figs 22.28A and B: Schematic diagram (A) and CT (B). Measurement of acetabular sector angles. H = Horizontal line through femoral head center, P = Posterior margin of acetabulum, A = Anterior margin of acetabulum, C = Center of femoral head, HASA = Horizontal sector angle, AASA = Anterior sector angle, PASA = Posterior sector angle

displaced. If the head is encompassed by the confines of the acetabulum and pointing at the triradiate cartilage, the pulvinar usually atrophies. Gadolinium enhanced magnetic resonance arthrography visualizes the labrum, ligamentum teres, transverse acetabular ligament and the pulvinar.20 In the immediate postoperative period, MR imaging is useful in evaluation of proper reduction of the dislocated femoral head and its vascular health. Recently dynamic interventional MRI in an open configuration scanner has been used in the management of developmental dysplasia. The hip can be visualized during reduction and spica can be applied within the scanner itself.21

Figs 22.29A and B: MRI T1 coronal (A) and T2 axial (B) shows dislocated femoral epiphysis with hypertrophied ligamentum teres preventing relocation

Differential Diagnosis of DDH Radiographic features such as shallow acetabulam with high angled roof lateral and cephalad displacement of the upper end of the femur and small ossification center for the head can be seen in congenital hypothyroidism. Following appropriate therapy, spontaneous resolution may occur. Traumatic epiphyseal separation of the femoral neck in very young infants may simulate congenital dislocation. The possibility of trauma may be considered if there is history of an abnormal presentation/difficult labor. Acquired non traumatic dislocation may develop in pyoarthrosis of hip. In such a case there will be clinical sign of infection will be present.

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The Painful Hip Hip pain in a child is always potentially serious and presents a diagnostic challenge since clinical differentiation between septic arthritis; transient synovitis and Perthes’ disease may be difficult. The principle concern is to distinguish sepsis of the hip joint from an irritable hip, as untreated sepsis can destroy the hip within days. The presentation may be mild and atypical and therefore imaging plays an important role in the management of such cases. Septic Arthritis Acute purulent infection of the joints is more common in infancy and early childhood because of greater blood flow to the joints during active growth. Hematogenous seeding is the most common cause related to an upper respiratory tract infection or pyoderma. Infection may also spread from adjacent osteomyelitis in metaphysis (specially in hip, where metaphysis is intra-articular) or from cellulitis, abscess, etc. During infancy, septic arthritis frequently complicates osteomyelitis because capillaries from the metaphysis traverses the physis into the epiphysis. Infants with immune dysfunction, indewelling cathetars, vascular lines are at increased risk. Over 90 percent of cases of septic arthritis are monoarticular with hip being one of the most commonly affected joints. Staphylococcus aureus is the most common cause of bacterial arthritis, with group B Streptococcus seen in neonates. H. influenzae in the 1-4 years age group. Children with chickenpox are at increased risk of developing septic arthritis and other musculoskeletal infections secondary to group A Streptococcus. Pneumococcal joint infection may be seen in children with splenic dysfunction. Over 90 percent of cases of septic arthritis are monoarticular with the hip being most commonly involved. Clinically there is fever, joint pain and swelling. Boys are affected twice as frequently as girls. It is a medical emergency as it may lead to joint destruction and impairment, if not immediately and adequately treated. Pathology The joint cartilage is a vascular and the synovial fluid cushions, lubricates, and nourishes the joint cartilage. Bacteria may seed into the synovial space through the highly vascular synovial membrane. Initially, there is edema and hypertrophy of the synovial membrane with joint effusion, which distends the joint. Hyperemia and immobilization leads to demineralization and osteoporosis. The ensuing inflammatory reaction results in destruction of the cartilage matrix leading to reduction of the joint space. Inflammatory pannus destroys the articular cortex, which is eroded. Severe cases are characterized by massive destruction, separation of bone ends, subluxation and dislocation. During recovery bones recalcify and bony and fibrous ankylosis may occur. Imaging Imaging evaluation is initially by conventional radiography. Plain films may be normal or demonstrate joint space widening with adjacent soft tissue swelling and disruption of normal tissue

Fig. 22.30: X-ray pelvis erosions in right femoral head with dislocation and widening of joint space septic arthritis

planes. It may show joint space loss and erosions with relative preservation of mineralization (Fig. 22.30). Radionuclide imaging is more sensitive than radiographs. A bone scan localizes the site of infection and is positive as early as 2 days after the onset of symptoms. In septic arthritis there is increased articular activity in the blood flow and blood pool phases. Reduced uptake within the epiphysis may be as a result of ischemia. Ultrasonography can clearly delineate presence and nature of joint fluid by direct visualization,22 and can be used to guide needle aspiration. The anterior approach along the plane of the neck is used as this is the most easily distensible part of the joint and fluid first accumulates in this area. In normal hip, the joint capsule is seen as a continuous concave reflective line paralleling the anterior aspect of the femoral neck and capital femoral epiphysis. Synovial thickening or an effusion causes the joint capsule to become convex and bulge anteriorly. A difference of 2 mm in the Anterior Capsule Distance (ACD) is indicative of effusion. Asymmetry is an unreliable parameter as effusion may be bilateral. The normal ACD increases with age and the upper limit of normal are 5 mm (50%) separates the two main groups A and B.45 DWI may be a noninvasive means of distinguishing between Perthes disease with favorable and unfavorable prognosis. Femoral epiphysis showed increased diffusivity in the affected hip. Increased metaphyseal diffusivity was found in all cases with absent lateral pillar enhancement at dynamic post contrast MR,46 signifying poor prognosis. The main differential diagnosis of LCP are toxic synovitis, septic hip, juvenile chronic arthritis and juvenile osteonecrosis (AVN due to a known cause-sickle cell anemia, thalassemia).

Proximal Femoral Focal Deficiency (PFFD) PFFD is a malformation in which complete growth and development of upper femur fails to occur. It encompasses spectrum ranging from mild shortening of an otherwise normal femur to severe handicap of absent femur, except for condyles accompanied by acetabular aplasia and thigh muscular dysplasia.

Fig. 22.48: X-ray pelvis—focal femoral deficiency in the right side

reossification progresses, the epiphysis regains a more uniform signal. With healing, proximal femoral epiphyseal height is slowly restored,ossific fragments coalesce and mature trabecular bone again constitutes the entire ossific nucleus. After approximately six years, the epiphysis shows normal MR signal. The extent and distribution of epiphyseal necrosis has prognostic implications. As the extent of femoral head necrosis increases, overall prognosis worsens. Prognosis is also adversly affected by the involvement of the lateral pillar, the lateral most one-third of the femoral head. Distubance of the physis is the single most important predictor of growth disturbance. Extensive

Imaging The radiographic findings consist of failure of development and delayed ossification of a lesser or greater part of the proximal femur. Hence, a short femur that is laterally situated and proximally displaced is demonstrated at birth. The distal femur is by definition always present (Figs 22.48 and 22.49), there is a misshapen femoral head and neck, upper end of disconnected distal femur- either bulbous or pointed. The femoral head is situated low in the acetabulum with a woolly outline. Secondary deformity of the acetabulum may result. In later cases, the greater trochanter will be found to curve like a beak and it may articulate with the ilium. Pelvis may show enlarged obturator foramen with a supra acetabular bump or horizontal/dysplastic roof of the acetabulum. If radiographs show a normal acetabulam at birth, presence of normal cartilaginous femoral head is likely. Hip sonography plays a role in the classification of PFFD and in confirming the location of the femoral head with respect to the acetabulum, especially when no proximal femur is seen on radiography. US may reveal a cartilaginous head and neck.47 Ultrasonography may be useful in prenatal diagnosis and in infants to identify the femoral head. Mobility of the femoral head within the acetabulum may also be assessed.48 MR imaging can identify correctly the size and position of the femoral head present. Thin section coronal and axial imaging is of use in locating a small femur head. Continuity to the rest of

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Fig. 22.49: Aitken class A PFFD: Femoral head is present and connected to the shaft of femur

the femur may also be assessed. Presurgical evaluation is important to guide the orthopedic surgeon in reconstruction. There may be a wide variation in the gap between femoral head and subtrochanteric femur. The gap may be small with pseudoarthrosis or be filled with fibro-osseous tissue. It can also be devoid of any connective tissue. This and the resultant coxa vara deformity cannot be adequately seen on a radiograph as the gap is radiolucent. On CT, the nonossified areas have soft tissue attenuation. On MRI, the femoral head, if present exhibits the intensity of yellow marrow, whereas fibrous tissue is low in signal intensity on all pulse sequence. The prognosis and treatment options depend on grading of the abnormalities. The most commonly used system is the Aitken classification which assigns types A to D to the abnormality depending in the presence or absence of the femoral head and the acetabulum and osseous integrity of the remainder of the femoral shaft. In patients with type A PFFD, the femoral is short. The femoral head and acetabulum are present. In type D the femur is very short and head and acetabulum are absent. Acetabular deformity is correlated with the presence or absence of the femur which can be inferred from the relative development of the acetabulum. The differential diagnosis can be a congenital short femur (no specific abnormalities of head, neck and shaft), Congenital coxa vara- Head, neck normal Developmental dysplasia of hip-Graf type 4 Traumatic femoral capital epiphysiolysis in newborn – Pain plus edema of inguinal crease and upper thigh is noted.

Slipped Capital Femoral Epiphysis Slipped capital femoral epiphysis (SCFE) is an uncommon skeletal disorder of adolescence often overlooked because of its non-specific presentation. It is a unique disorder because no other bone shows similar changes. It is usually seen during adolescent

growth spurt in overweight children, with the incidence of bilaterality being 25 percent. There is a morphological change in the relationship of the femoral head to the femoral neck centered at the physeal level probably caused by obesity. The femoral head becomes relatively retroverted at the physeal level placing the head and physis at a mechanical disadvantage when subjected to stress. It is Salter 1 fracture through the proximal femoral physis with displacement of the capital femoral epiphysis. In most cases, the displacement of the head is usually medial and posterior relative to the metaphysis. In a few cases, there may be a valgus slip with the head rotating superiorly and posteriorly relative to the neck. This term does not include traumatic Salter-harris 1 as the etiology and management are different. The most common sign/symptom is limp, painful limitation of hip motion while walking/running .It coincides with adolescent growth and is related to endocrine disorders like hypothyroidism, pituitary dysfunction. The slip is classified as stable or unstable with the criterion being the ability to bear weight with or without crutches. The incidence of complications is higher with unstable variety.

Imaging Radiographs remain the prime method of diagnosing SCFE, though it may be difficult to diagnose on anterior projection alone. Medial displacement of the capital epiphysis is seen on the antero posterior projection. A line drawn along the lateral border of the femoral neck (Klein line) in a normal individual intercepts the epiphyseal ossification center so that a small portion of the head remains lateral to this line (Fig. 22.50A and B). With SCFE, no part of femoral head ossification center is seen lateral to the line. On the anterior projection, there may be mild widening, lucency and irregularity of the physis. The femoral head may appear foreshortened and there may be apparent sclerosis in the regional femoral neck as the femoral head rotates posteriorly. In the frogleg or true lateral position, the anterior and posterior corners of the epiphysis and metaphysis line up closely in a normal patient, whereas they are displaced in SCFE (Figs 22.51 and 22.52A & B). Posterior displacement is seen on frog lateral radiograph as medial displacement of epiphysis relative to metaphysis. Approximately 90° external rotation of femur on frog-lateral means what is actually a posterior displacement of epiphysis looks like medial displacement on radiograph. On the cross table lateral radiograph with 25 flexion, it is seen as true posterior displacement of epiphysis. Metaphysis shows scalloping, irregularity, sclerosis and posterior beaking. One needs to be careful when using opposite asymptomatic hip as control for radiographic evaluation of painful one as the opposite side may have unrecognized SCFE. Staging of radiographic findings is mild- moderate- severe based on the displacement of ossification center by < 1/3 – 1/32/3 – > 2/3 metaphyseal diameter. Ultrasound may suggest malalignment of the capital femoral epiphysis relative to the metaphysis.4 The alignment of the epiphysis relative to the metaphysis should be assessed as part

Chapter 22 ™ Imaging of Pediatric Hip 375

Figs 22.50A and B: Schematic representation: (A) of hip shows Klein’s line that normally intersects lateral 1/3rd of the femoral epiphysis on the left, whereas in slipped epiphysis, no part of the epiphysis in lateral to it as seen on the right. X-ray pelvis. (B) Depicting the normal position of the femoral head in relation to the Klein’s line

Fig. 22.51: X-ray pelvis—Slipped capital epiphysis left side

of hip ultrasound study. Joint effusion, which may accompany SCFE, is recognized by US. US can be used as follow-up of SCFE due to risk of slippage in the contralateral hip.49 CT demonstrates the slip and the reduced femoral anteversion, which may be quantified CT head/neck angles range from 4-57 degrees in symptomatic and 0-14° in asymptomatic patient.50 It may also demonstrate metaphyseal scalloping and beaking (Figs 22.53A to C). MR imaging relies on identification of the morphological change at head/neck function and the abnormal signal intensity

centered on the physis, indicating stress and edema. Physeal widening is a constant feature and can be seen on MR before being apparent on radiographs. 3D volume acquisition can be used to reconstruct sagittal oblique images along the axis of the femoral neck to identify any retroversion. MR image can be oriented to a plane orthogonal to the plane of the physis to assess the width of the same. Physeal widening is seen on T1 weighted MRI, whereas synovitis and marrow oedema are appreciated on T2 weighted images (Figs 22.54A and B). MRI can also demonstrate physeal widening in the center or posteromedial origin of the physis in a contralateral asymptomatic hip, providing for prophylactic treatment of the same.51 Hyperintensity on fluid sensitive images at the physis is indicative of a chronic slip condition. Subtle abnormalities include edema on the metaphyseal side, usually at the extreme medial end of the physis. The complications of SCFE are avascular necrosis, occurring in 20-45 percent of cases and chondrolysis. Treatment consists of preventing further displacement and to cause closure of the physis. Chondrolysis is less common than AVN and is recognized by progressive thinning of the medial joint space on the radiographs. Premature closure of the physis of the greater trochanter is considered as predictive sign for chondrolysis. Premature osteo arthritis may develop in ¼-1/3 of patient with SCFE. Prognosis is poorer with unstable variety.

The differential diagnosis includes • Legg-Calve-Perthes’s disease—the patient is younger with irritable hip progressing to sclerosis and collapse of epiphysis, there is a hairline fracture with marrow edema: • Hip joint inflammation • Osteoid osteoma • Traumatic SCFE

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Figs 22.52A and B: X-ray frog’s leg view (A) and AP view(B) –shows medial and inferior displacement of the right capital epiphysis with widening of the physis

Developmental Coxa Vara The normal femoral neck shaft angle changes from about 150 degrees in the infant decreasing to 120° in the adult. The femoral neck is valgus in infants because of relatively increased growth in the medial portion of the physis in the perinatal period. During childhood there is a greater amount of growth in the lateral portion of the femoral physis that is influenced by weight bearing. Coxa vara is defined as femoral neck shaft angle of less than 120°.52 True coxa vara may be secondary to congenital anomalies, osteomalacia, or syndromes. Functional coxa vara occurs as a result of overgrowth of the greater trochanter secondary to AVN, infection or trauma. Developmental coxa vara, bilateral in 40 percent of cases, presents at 2 years of age with an abnormal

Figs 22.53A to C: CT – Coronal MPR (A), Axial (B) and VRT (C) Medial and posterior slip of the femoral epiphysis of the right hip with complication of avascular necrosis as seen by flattened head of femur

Chapter 22 ™ Imaging of Pediatric Hip 377

Fig. 22.55: Right coxa vara

Figs 22.54A and B: (A) MRI-T1 weighted coronal and (B) STIR coronal depicting widening and irregularity of the physis on the left side with physeal slip—Slipped capital femoral epiphysis

gait. It is caused by an abnormality of bone growth at the physis with a greater rate of growth of the lateral aspect of the physis causing the physis to be more vertical than usual. Radiographs show a widened and an abnormally oriented physis (Fig. 22.55). As stress occurs along the physis multiple small steps occurs and small triangular corner fractures develop along the medial aspect of the physis. MR imaging demonstrates widening of the physis with expansion of the cartilage.

Pediatric Hip Trauma Traumatic hip dislocations rarely occur in childhood. Posterior hip dislocations comprise majority of such dislocations.53 A soft pliable acetabulum and ligamentous laxity may predispose the

immature hip joint to a dislocation secondary to minimal trauma. Potential associated injuries include fracture and neurovascular injury while avascular necrosis and degenerative joint disease are potential sequelae. Osteochondral fractures may be difficult to recognize on plain radiography. CT is useful in the definition of the extent and displacement of complex and impacted fractures around the hip joint. Growth plate injuries are important to recognize as they have potential implications for growth arrest. Growth disturbance of the proximal femur can be post-traumatic or may be secondary to ischaemia following hyperabduction for DDH, Legg-CalvePerthes’ disease and rapidly developing effusions. The proximal femur physis is particularly vulnerable because the epiphyseal artery is intraarticular physeal widening or narrowing may be seen on radiographs. MR imaging is the modality of choice. T1 weighted images demonstrate low signal intensity growth recovery line and variable signal intensity bony bridge on GRE sequences, a bridge appears as a low signal intensity interruption in high signal physeal cartilage. Physeal widening on GRE and T2 weighted images implies physeal dysfunction. Medial physeal impairment leads to a short wide femoral neck and coxa vara deformity whereas vertex arrest causes Coxa valga54 (Figs 22.56A & B and 22.57).

Neuromuscular Hip Dysplasia Children who suffer from cerebral palsy or other neuromuscular disorders, who are unable to walk have a 58 percent incidence of hip dislocations. With muscle imbalance and lack of weight bearing, there is a coxa valga deformity with persistence of a straight neck shaft angle, which leads to hip dislocation. Simulated standing radiographs show pelvic tilt, valgus deformity of the femoral neck, abnormal shape and placement of the femoral head. CT is helpful in evaluate the shape of the acetabulum and the degree of femoral articulation.

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Figs 22.56A and B: X-ray pelvis (A)—Traumatic posterosuperior dislocation of the left femur, MRI-T1 coronal (B) depicting the superior and posterior dislocation

injection via the femoral route. On serial studies, calcification may remain unchanged, increase, or show gradual resorption with early fusion of the femoral head and neck. The hip joint may also be involved as part of a large number of skeletal dysplasias or systemic disorders as in nutritional disorders, neoplasia like leukaemia, metastatic neuroblastoma. Developmental and acquired abnormalities of the hip are relatively common in childhood. Radiographs, ultrasonography, MR imaging, computed tomography and nuclear medicine play an important role in the diagnosis and management of these disorders.

Fig. 22.57: X-ray pelvis—Fracture right femoral neck

Childhood Idiopathic Chondrolysis of the Hip This is a rare disorder, which causes progressive destruction of the articular cartilage of the hip joint with associated bone remodeling. Cartilage loss, bone remodeling, and small joint effusions along with muscle wasting are seen.55 Calcification of Cartilage and Joints Idiopathic calcification of the cartilages of the hips, i.e. acetabular rims and femoral hands has been reported in children and the patients may be asymptomatic or have a limp with restricted hip movements. This is believed to be an acquired pathology due to local chemical trauma from partial extravasation of an intravenous

Femoroacetabular Impingement The geometry of femoral neck and acetabulum plays a role in the etiology of degenerative disease.56,57 Normally, the femoral neck has a definite narrowing or waist which allows the femur to abduct fully without impingement on the lateral aspect of the acetabulum. In patients with FAI, the femoral neck is not tabulated normally. Instead of having an identifiable constriction, a pistol grip deformity is seen in which tabulation is lacking. A small bump or protuberance may be identified on the anterior femoral neck. Slipped capital femoral epiphysis may be a contributing factor (Fig. 22.58). Axial oblique images prescribed along the axis of the femoral neck or reconstruction of 3D volume acquisition into axial oblique plane allows for measurement of α angle. First the center of the femoral head is identified using the contour of the head to fit a circle to outline and define the position of the center of the head. Two lines are extended from the center point of the head, one down the axis of the femoral neck and the second to the intersection point between the head and the neck, when the convexity of the femoral head becomes the concavity of the femoral neck. Angles less than 55° are abnormal or if the

Chapter 22 ™ Imaging of Pediatric Hip 379

7. 8. 9. 10. 11. 12. 13. 14. 15. Fig. 22.58: CT—Oblique axial image shows evidence of CAM impingement with a bump at the femoral neck

head-neck line measures greater than the radius of the circle defining the femoral head, then a femoral waist deficiency is present. FAI may also be caused by over coverage of the femoral head and neck. This may be caused by acetabular retroversion. Normally the acetabulum has its lateral opening directed slightly anteriorly. In abnormal cases, the anterolateral edge of the acetabulum extends further laterally than the posterolateral edge so that the acetabular opening is directed posteriorly. On radiographs,this is visualized as the cross over sign. This is present when the anterior lip of the acetabulum crosses over the posterior lip on a standard frontal film. This limits the ability to flex at the hip as the femoral neck impinges on the anterior acetabulum. Abnormal morphology in the pediatric age group may not reflect the pathological abnormalities seen in adulthood, however subtle osseous abnormalities can help guide prognosis.

REFERENCES 1. Jacobs P, Renton P. Congenital anomalies: Skeletal dysplasias; chromosomal disorders. In Sutton D(Ed): Textbook of Radiology and Imaging (4th edn). Churchill Livingstone 1987; 1:2-50. 2. Hilgenreiner H. Zur Fruhdiagnose and Fruhbehandlung derangegorenen Huftgelenkrerrenkueg Med Klink 1925; 21:138588,1425-29. 3. Andren L, von Rosen S. The diagnosis of dislocation of hip in newborns and the preliminary results of immediate treatment. Acta Radiol 1958; 49:89-95. 4. Gibbon Wayne W, Long G. In Meire H, Cosgrove D, Dewbury K, et al (Eds): Musculoskeletal System: Abdominal and General Ultrasound (2nd edn). London: Churchill Livingstone 2000; 2. 5. Fayed LM, Johnson P, Fishman EK. Multidetector CT of musculoskeletal disease in pediatric patient;principles,techniques and clinical applications. Radiographics 2005; 25:603-61. 6. Jaramillo D, Galen TA, Winalski CS, et al. Legg-Calve-Perthes disease: MR imaging evaluation during manual positioning of the

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hip-comparison with conventional arthrography. Radiology 1999; 212(2):519-25. Aubry S, Belanger D, Giguere C. Magnetic resonance arthrography of the hip: Insights Imaging 2010;1:72-82. Klisie PJ. Congenital dislocation of the hip: A misleading term. J Bone Joint Surg Br 1981;63:38-42. Kuhn JP, et al. Caffey’s Pediatric Diagnostic Imaging. 10th edn 2277-9,2004: Mosby. The joints BabynPS, RansOm MD 2435-93. Havije HT, Waller RS. Ultrasound screening for dysplasia of the hip (Letter). Pediatrics 1995; 95:799-800. Zieger M. Ultrasound of the infant hip Part 2 validity of the method. Pediatric Radiol 1986; 16:488-92. Graf R. Classification of hip joint dysplasia by means of sonography. Arch Orthop Trauma Surg 1984; 102:248. Harcke HT, Lee MS, Born P, et al. Examination of the infant hip with real time ultrasonography. J Ultrasound Med 1984; 3:131. Harcke HT, Grissom LE. Performing dynamic sonography of the infant hip. AJR Am J Roentgenol 1990; 155:837. Rosendahl k, Toma P. Ultrasound in the diagnosis of developmental dysplasia of the new borns. The European approach. A review of methods, accuracy and clinical validity: Eur Radiol 2007; 17:1960-7. Schwartz DS, Kellar MS, Fields JM, et al. Arterial waveforms of the femoral heads of healthy neonates. AJR Am J Roentgenol 1998; 170:465-66. Browing WH, Rosenkrantz H, Tarquinio T. Computed Tomography in congenital hip dislocation. J Bone Joint Surgery (AM) 1982; 64:27-31. Hubbard AM. Imaging of pediatric hip disorders. Rad Clin North Am 2001; 39(4). Dwek JR. The Hip: MR Imaging of Uniquely Pediatric Disorders: Radiol Clin North Am 2009; 47:997-1008. Kawaguchi AT, Otsuka NY, Deigado ED, et al. Magnetic resonance arthrography in children with developmental hip dysplasia. Clin Orthop 2000; 374:235-46. Tennant S, Kinmant C, Lamb G, et al. The use of dynamic interventional MRI in developmental dysplasia of the hip. J Bone Joint Surg B 1999; 81(3):392-97. Jawin J, Hoffer F, Rand F, et al. Joint effusion in children with an irritable hip: Ultrasound diagnosis and aspiration. Radiology 1993; 1987:459. Strouse PJ, Di Pietro MA, Adler RS. Hip Effusions: Evaluation with Power Doppler Sonography. Radiology 1998; 206:731-35. Hopkins K, Li K, Bergmon G. Gadolinium DTPA enhanced magnetic resonance imaging of musculoskeletal infections processes. Skeletal Radiol 1995; 24:325. Lee SK, Suh KJ, Kim YW, et al. Septic arthritis, versus transient synovitis at MR imaging preliminary assessment with signal intensity alterations in bone marrow. Radiology 1999; 211:459. Park JK, Kim BS, Choi G, et al. Distinction of reactive joint fluid from pyogenic abscess by diffusion–weighted imaging. J. Magn Reson Imaging 2007; 25(4):859-61. Daldrup-Link HE, Steinbach L. MR imaging of Pediatric arthritis Radiol Clin N Am 2009; 47:939-55. Hong SH, Kim SM, Ahn JM, et al. Tuberculous versus pyogenic arthritis: MR imaging evaluation. Radiology 2001; 218:843-53. Sawhney S, Jain R. Tuberculosis of the bones and joints. In Berry, Chowdhury, Suri (Eds): Diagnostic Radiology-Musculoskeletal and Breast imaging (1st edn). Jaypee Brothers 1998. Chapman H, Murray RD, Stoken OJ. Tuberculosis of the bone and joints. Semin Roentgenol 1979; 19:26-282.

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31. Murray RO, Jacobson HG. Infections: Radiology of Skeletal Disorders (2nd edn). Churchill Livingstone 1997; 1. 32. Jacobs P, Renton P. Avascular necrosis of bone: Osteochondritis: Miscellaneous bone lesions. In Sutton D (Ed): Textbook of Radiology and Imaging (4th edn). Churchill Livingstone 1987; 1:7794. 33. Caterall A. Legg-Calve-Perthes disease. New York, Churchill Livingston 1982. 34. O’hara SM. Benton C-abnormalities of hip in Diagnostic ImagingDonelly. Amirsys 2005. 35. Doria AS, Guarniero R, Gunha FG, et al. Contrast enhanced power Doppler Sonography: Assessment of revascularization flow in LeggCalve-Perthes’ disease. Ultrasound Med Biol 2002; 28(2):171-82. 36. Strouse PJ. Musculoskeletal system. In Haaga JR, Lanzieri, Gilkeson (Eds): CT and MR Imaging of the Whole Body (4th edn) 2002; 2:2095-122. 37. Ha As, Wells J, Jaramillo D. Importance of sagittal MR imaging in nontraumatic femoral head osteonecrosis in children. Pediatr Radiol 2008; 38(ii):1195-200. 38. Jaramillo D, Galen TA, Winalski CS, et al. Legg-Calve-Perthes’ disease: MR imaging evaluation during manual positioning of the hip. Comparison with conventional arthrography. Radiology 1999; 212(2):519-25. 39. Dillman JR, Hernandez RJ. MRI of Legg-Calve-Perthes disease. AJR 2009; 193:1394-1407. 40. Mahnken AH, Staatz G, Ihme IV, et al. MR signal intensity characteristics in Legg-Calve-Perthes’ disease value of fat suppressed (STIR) images and contrast enhanced T1 weighted images. Acta Radiol 2002; 43(3):329-35. 41. Lamer S, Dogeret S, Khairouni A, et al. Femoral head vascularization in Legg-Calve-Perthes’ disease Comparison of dynamic gadolinium enhanced substraction MRI with bone scintigraphy. Pediatric Radiol 2002; 32(8):580-85. 42. Menezes NM, Olear EA, Li X, et al. Gadolinium enhanced MR images of the growing piglet skeleton: Ionic versus. Nonionic contrast agent. Radiology 2006; 239(2):406-14. 43. Menezes NM, Connolly SA, Shapiro P, et al. Early ischemia in growing piglet skeleton. MR diffusion and perfusion imaging. Radiology 2007; 242(1):129-36.

44. Lahdes-Vasama T, Lamminen A, Merikanto J, et al. The Value of MRI in early Perthes’ disease: An MRI study with a 2 year follow up. Pediatric Radiol 1997; 27(6):517-22. 45. De Sanctis N, Rega AN, Rondinella F. Prognostic evaluation of Legg-Calve-Perthes’ disease by MRI-Pathomorphogenesis and new classification. J Pediatr Orthop 2000; 20(4):403-70. 46. Merlinic L, Combescure C, De Rosa V, et al. Diffusion – weighted imaging findings in perthes disease with dynamic gadolinuim – enhanced subtracted (DGS) with MR correlation – a preliminary study Pediatr Radiol 2010; 40(3):31. 47. Grissom LE, Harcke HT. Sonography in congenital deficiency of the femur. J Paediatr Orthop 1994; 14:29-33. 48. Kayser R, et al. Proximalfocal femoral deficiency – rare entity in the sonographic differential diagnosis of developmental dysplasia of the hip. J Pedia tr 2005; 146(1):141. 49. Castriota-Scandfrberg A, Orsi E. Slipped capital femoral epiphysis ultrasonographic findings skeletal. Radiol 1993; 22(3):191-93. 50. Umans H, Liebling MS, Moy L, et al. Slipped capital femoral epiphysis: A physeal lesion diagnosed by MRI with radiographic and CT correlation. Skeletal Radiol 1998; 27(3):139-44. 51. Futami T, Suzuki S, Seto Y, et al. Sequential magnetic resonance imaging in slipped capital femoral epiphysis, assessment of prestep in the contralateral hip. J Paediatr Orthop B 2001; 10(4):298-303. 52. Ozonof MB. Pediatric Orthopaedic. Radiology Philadelphia: WB Saunders 1992. 53. Petrie SG, Harris MB, Willis RB. Traumatic hip dislocation during childhood. A case report and review of the literature. Am J Ortho 1996; 25(a):645-49. 54. Ecklund K, Jaramillo D. Imaging of growth disturbance in children. Radiol Clin North Am 2001; 39(4):823-42. 55. Johnson K, Haigh SF, Ehtisham S, et al. Childhood Idiopathic Chondrolysis of the hip: MRI features. Paediatr Radiol 2003; 33(3):194-99. 56. Pfirrmann CW, Mengiardi B, Dara C, et al. Ca M and pincer femora acetabular impingement: Characteristic MR authrographic findings in 50 patients. Radiology 2006; 240(3):778-85. 57. Gam R, Parvizi J, Beck M, et al. Femoracetabular impingement: A cause of osteo arthritis of the hip. Clin Orthop Relat Res 2003; 417:112-20.

chapter 23

Benign Bone and Soft Tissue Tumors and Conditions Mahesh Prakash, Kushaljit Singh Sodhi

Benign bone tumor and tumor like lesions are very common in children. More than half of all childhood bone neoplasms are benign.1 It is important that radiologists recognize the typical imaging features of benign tumors so that patient can avoid unnecessary diagnostic and surgical procedures. The differential diagnosis of bone tumors can be narrowed, based on knowledge of age of the patient, gender, constitutional complaints, location of the lesion in body and bone and general radiographic characteristics.2 Plain film radiographs remain the primary tool for evaluating bone tumors. However, other imaging methods, particularly magnetic resonance imaging (MRI) and in some cases computed tomography (CT) and nuclear studies, provide support for initial diagnosis by demonstrating specific features. 1,2 Common benign bone lesions in children are osteochondroma, nonossifying fibroma, Langerhans’ cell histiocytosis, unicameral bone cyst and aneurysmal bone cyst. Benign bone tumors and tumor like lesions in children may be classified as follows:1 1. Cartilaginous tumors a. Osteochondroma b. Enchondroma c. Chondroblastoma d. Chondromyxoid fibroma 2. Osseous tumors a. Osteoid osteoma b. Osteoblastoma 3. Fibrous tumors a. Nonossifying fibroma b. Fibrous dysplasia c. Osteofibrous dysplasia 4. Langerhans cell histiocytosis 5. Giant cell tumor 6. Tumor like lesions a. Simple bone cyst b. Aneurysmal bone cyst c. Pseudotumor of hemophilia

CARTILAGINOUS TUMORS Osteochondroma Osteochondromas are common lesions of the growing skeleton, occurring in approximately 1 percent of the general population. It is the most common benign neoplasm and constitutes 20-50 percent of all benign tumors.3 They arise from bony metaphysis with cartilage cap covering (Fig. 23.1). These tumors are either pedunculated or sessile. The long axis of the osteochondroma pedicle or stalk is almost always directed away from the adjacent joint. The direct communication between the osteochondroma and the cortex and marrow cavity of the bone from which it arises is a distinctive feature, that is particularly well demonstrated on computed tomography and magnetic resonance imaging. T2

Fig. 23.1: Osteochondroma—Radiograph of lower end of femur (AP and Lat view) shows large well defined bony outgrowth, with broad based attachment to femur

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Fig. 23.2: MRI (T1W fat sat), Axial section of the same patient shows clear demonstration of continuity of marrow and cortex of host bone into osteochondroma with covering cartilage cap

Fig. 23.3: Diaphyseal aclasia—PA radiograph of bilateral hands show multiple pedunculated osteochondromas, involving multiple bones of hands and forearm

weighted MR images is useful to demonstrate an cartilaginous cap (Fig. 23.2). The cap can be quite thick in early childhood and like the normal physis, becomes thinner with age. After epiphyseal closure, growth of the osteochondroma ceases. Multiple osteochondroma occur as a manifestation of diaphyseal aclasia, an inherited disorder with autosomal dominance (Fig. 23.3). Because most osteochondromas are asymptomatic, they are usually discovered incidentally. However, mechanical irritation of adjacent soft tissues or nerves, vascular injuries, fracture of the stalk, or malignant transformation can produce symptoms. Malignant transformation into low grade chondrosarcoma occurs in 1 percent of osteochondromas, however, the risk is 10 to 30 percent in cases of multiple osteochondromatosis.3,4 Malignant transformation should be considered when the osteochondroma grows after epiphyseal closure. Malignancy occurs in the cartilaginous cap, which becomes thickened. The cap of an osteochondroma usually measures less than 1 cm in thickness, whereas that of a chondrosarcoma often exceeds 2 cm.

Enchondroma Enchondromas accounts for 12 percent of benign bone tumors.3 These are most frequently located in the large and small tubular bones of the limbs, particularly those of the hand (Fig. 23.4). Like other cartilaginous tumors, enchondromas exhibit a lobulated growth pattern, that results in asymmetric expansion of the medullary cavity and endosteal scalloping. Tumor matrix may be radiolucent or show calcification. Characteristic cartilaginous ring and arc pattern of calcifications is seen on radiographs and CT images. On MR imaging, the tumor is isointense to muscle on T1 weighted and exhibits a heterogeneous, predominantly high T2 weighted signal.5 Contrast enhanced MRI may demonstrate a pattern of thin arcs and rings.

Fig. 23.4: Enchondroma—Radiograph shows a sharply demarcated expansile lytic lesion with pathological fracture in the middle phalanx of index finger

Ollier’s disease is a nonheritable disorder of cartilage proliferation in which enchondromas involve multiple bones, especially those of the hands and may result in severe skeletal deformity. Enchondromatosis accompanied by multiple hemangiomas is known as Maffucci’s syndrome. Calcified phleboliths may be demonstrated radiographically in the hemangiomatous soft tissue masses. Lesions associated with both Ollier’s disease and Maffucci’s syndrome carry a significant risk of malignant degeneration (30-70%).6

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Fig. 23.5: Chondroblastoma—CT (coronal reformation) shows lytic lesion in epiphysis of upper humerus with matrix calcification

Chondroblastoma It is less common than enchondroma. Chondroblastoma is composed of primitive cartilage cells, usually occurs in the age group of 10-20 years. It is typically located in epiphysis and apophysis of bone, most often the proximal humerus, distal femur, or proximal tibia. On plain X-ray, chondroblastoma is an eccentric, lucent, well defined lesion with sclerotic borders. Periosteal reaction, far from the lesion is another common feature suggesting an accompanying inflammatory process. Approximately one third of chondrobastoma have a calcified matrix which can be better seen on CT scan (Fig. 23.5). The tumor shows signal intensity similar to that of muscle on MR imaging; however, the rim of the tumor has lower signal intensity. On T2 weighted images, the signal intensity of the tumor is low to intermediate. This tumor also shows extensive surrounding inflammation which may be confused with more aggressive lesion. Malignant transformation of chondroblastoma is extremely uncommon.7 Chondromyxoid Fibroma Chondromyxoid fibroma is less common than chondroblastoma, affecting predominantly males in the age group of 15 to 35 years.8 Histologically it is composed of chondroid, myxoid and fibrous tissue in varying amounts. The common locations of tumor are ilium and the bones of the knee and foot. These tumors are located characteristically in metadiaphyseal location unlike chondroblastoma and do not cross an open growth plate. On plain radiograph, it appears as a well marginated central or eccentric lucent lesion, with sclerotic margins and cortical expansion (Fig. 23.6). Half of the lesions may show parallel orientation to the long axis of the involved bone. Matrix calcification and periosteal new bone formation usually do not occur.

Fig. 23.6: Chondromyxoid fibroma—Radiograph of right hip shows large expansile lesion with sclerotic border involving right acetabulum

OSSEOUS TUMORS Osteoid Osteoma Osteoid osteoma is a fairly common tumor, accounting for approximately 10-12 percent of all benign tumors.9 These tumors usually affect boys in the second decade of life. Clinically most patients presents with pain that is especially severe at night and relieved by aspirin or other nonsteroidal antiinflammatory agents. More than half of tumors are located in proximal femur and tibia. They occur less frequently in the upper extremities than in the lower extremities. Osteoid osteomas also frequently affect the tubular bones of the hands and feet. They are however less common in the spine, where they affect the posterior arches of the vertebra. Histologically, the lesion consists of a nidus which is usually surrounded by dense sclerotic bone. The nidus contains interlacing trabeculae at various stages of ossification within a stroma of loose, vascular connective tissue. Osteoid osteoma can be cortical (the most common type), cancellous or medullary, and subperiosteal. The latter two types produce less sclerotic bone than those in the cortex do, making radiologic diagnosis difficult. Radiographically, the lesion appears as well defined lytic lesion, surrounded by reactive sclerosis (Figs 23.7A and B). Solid or lamellated periosteal reaction is seen in 60 percent of patients. Nidus may be purely radiolucent or contain a dense center. Intraarticular osteoid osteomas may be either cancellous or periosteal and have little reactive bone or periosteal new bone formation. CT is very useful in showing the nidus, which can vary in its degree of ossification. CT appears to display the nidus better than MRI. The tumor nidus typically shows hypo to intermediate signal on T1W images and low to high signal on T2W images. The nidus shows enhancement with gadolinium.10 Intra-articular osteoid osteomas produce joint effusions and synovial proliferation. Radionuclide bone scans have been used for many years to help

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Figs 23.7A and B: Osteoid osteoma—Radiograph of leg (A) shows dense sclerosis and solid periosteal reaction in the diaphysis of tibia. CT scan axial sections reveals well defined lytic lesion with calcified nidus with gross adjacent sclerosis (B)

Fig. 23.8: Osteoblastoma—MRI axial section, T1 and T2WI images reveals heterogeneous signal lesion, predominantly involving posterior elements of vertebra with extension into spinal canal and left paravertebral location

diagnosis of osteoid osteomas. Bone scintigraphy, which is a highly sensitive method of detecting osteoid osteoma typically shows increased flow to the lesion on immediate images and a focus of increased activity on skeletal equilibrium images with double density sign. Many times, osteomyelitis can mimick osteoid osteoma clinically as well radiographically, however, presence of soft tissue extension favors the diagnosis of osteomyelitis. The traditional treatment of choice has been surgical excision, however, it can also be successfully treated by radiofrequency ablation under image guidance.11

Osteoblastoma Osteoblastoma constitutes 2 to 6 percent of all bone tumors and most commonly occurs in patients in the second and third decade

of life.12 This tumor is more common in males than in females. Histologically, the osteoblastoma is closely related to osteoid osteomas except that bony trabeculae are broader and longer with absence of surrounding sclerotic halo. Size is an important consideration in distinguishing between these two types of tumors. If the size of lesion is less than 1.5 cm in diameter than it is likely to be osteoid osteomas, whereas tumors larger than 1.5 cm are usually osteoblastoma. The most common location of osteoblastoma is spine where it classically affects posterior elements (33%)12 (Fig. 23.8). The other common locations are proximal femur and talus. On plain X-ray, spinal osteoblastoma is osteolytic lesion with destruction of overlying cortex and may extend to in the spinal canal. In the long bones, osteoblastoma appear radiologically as round or oval

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Fig. 23.9: Nonossifying fibroma—Radiograph of knee joint (Lat view) shows well defined lytic lesion with sclerotic margin in characteristic location of lower end of femur

Fig. 23.10: Fibrous dysplasia—Radiograph of pelvis shows multiple lytic lesions involving all the visualized bones with characteristic Shepherd’s crook deformity

lucent tumors in the medulla. Periosteal reaction is common. Edema in the soft tissues or marrow appears hyperintense on T2 weighted images but the signal characteristics are not specific. Treatment is by surgical excision or curettage, but there is a moderate recurrence rate after these procedures.

neoplasm, fibrous dysplasia involving a long bone may mimic a bone tumor or cyst. This type of fibrous dysplasia causes expansion of the medullary cavity of tubular bones, endosteal scalloping and trabeculation. The margin is sclerotic. The lesion may appear as ground glass or radiolucent, and this depends upon amount of fibrous tissue within the lesion. Bowing of the affected long bone may occur; when the affected bone is femur, the resulting deformity is called a “Shepherd’s crook” (Fig. 23.10). Thinning and destruction of the bony cortex may be seen on CT or MR images. Soft tissue extension of the lesion is unusual. On T1-weighted MR images, the signal intensity of fibrous dysplasia is similar to that of skeletal muscle. Although, the signal of pure fibrous tissue is hypointense on T2-weighted images, the signal of fibrous dysplasia is variable.

FIBROUS TUMORS Nonossifying Fibroma Nonossifying fibroma is a benign fibroblastic mass that occurs in long bones of children and represents continuation of growth of fibrous cortical defect. It occurs eccentrically in the medullary cavity. The common location of lesion is in the bones around the knee joints. These lesions are usually asymptomatic and do not require specific treatment. On plain radiography, the lesion appears as well marginated eccentric lytic lesion with scalloped margin (Fig. 23.9). Its inner border is often sclerotic and may appear multilocular due to corrugations. Differential diagnosis includes unicameral bone cyst, aneurysmal bone cyst, fibrous dysplasia, and chondromyxoid fibroma. The signal intensity of nonossifying fibroma is equal to or less than muscle on T1 weighted MR images and hypointense to fat on T2 weighted images. Postcontrast images usually show heterogeneous enhancement. Fibrous Dysplasia Fibrous dysplasia is disorders where bone is replaced by abnormal fibrous tissue. Fibrous dysplasia can be monostotic, polyostotic, monomelic, or polymelic. It is more common in young females. It is occasionally seen in the first decade of life. In a small percentage of cases (2-3%), fibrous dysplasia is associated with endocrine disorders, especially precocious puberty in girls (McCune-Albright syndrome).13 Although it is not a true

Osteofibrous Dysplasia It is a rare lesion that is usually confined to the tibia but can also involve the fibula. Most cases occur during the first decade of life. On plain X-ray, the lesion appears as an eccentric, lucent, solitary or multiloculated, lesion involving the anterior aspect of tibia. CT is very helpful in determining its intracortical location, an important feature in distinguishing osteofibrous dysplasia from fibrous dysplasia.14 HISTIOCYTOSIS X (LANGERHANS CELL HISTIOCYTOSIS) Histiocytosis X is a syndrome that consists of group of clinical pathological entities: eosinophilic granuloma, Hand-SchülerChristian disease and Letterer-Siwe disease. Eosinophilic granuloma is localized skeletal disease and is one of the commonly occurring bone tumors of boys in the first decade of life. 15 The skull is the most frequent location, followed by the femur, mandible, pelvis, ribs and spine. The lesions are usually

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Fig. 23.11: Histiocytosis—Radiograph of skull (Lat view) shows well defined lytic lesion with beveled margins in frontal lobe

Fig. 23.13: Histiocytosis – MRI of femur shows large heterogeneous signal intensity lesion in diaphysis with cortical destruction, soft tissue and periosteal reaction

may be seen in the lesion. Most of the lesions in long bones appear as lytic lesion with well defined borders, however some of the lesions are permeative and associated with periosteal new bone formation (Fig. 23.12). The later findings suggest aggressive behavior. MRI is a very sensitive but non-specific method of detecting eosinophilic granuloma. The lesion can be hypointense or hyperintense on T1 and hyperintense on T2W images, associated with extensive marrow and soft tissue edema. Occasionally, there is cortical disruption with adjacent soft tissue seen on MRI (Fig. 23.13). The natural history of isolated lesion is gradual healing.16 Treatment depends upon the site, location and multiplicity of lesion.

Fig. 23.12: Histiocytosis—Radiograph of the pelvis and upper femora shows multiple well defined and ill-defined lesions with associated periosteal reaction in both femora

located in the medulla of the diaphysis and metaphysis and rarely involves the cortex and epiphysis. Multiple lesions occur in about 25 percent of cases.15 Pain is most common presenting problem with local tenderness and palpable mass. Histologically, the tumors are composed of Langerhans histiocytes containing their characteristic cleaved nuclei, and electron microscopy reveals Birbeck granules in the cytoplasm adjacent to the cell membrane. Radiographic appearance is variable. The lesion in calvarium typically appears as well defined lytic lesion with scalloped/ beveled borders (Fig. 23.11). Sometimes, a button sequestrum

GIANT CELL TUMOR Giant cell tumors are very rare in children under 15 years of age, and commonly seen in girls.17 Radiographically, these tumors are well defined, eccentric lytic lesions usually located around the knee. The lesion usually shows nonsclerotic margin, cortical thinning without matrix calcification (Fig. 23.14). GCT is located in the metaphysis and do not cross the open physis, but may extend to the subchondral bone if the physis is closed. On MRI, the lesion shows generalized hypointensity on T2-weighted images. This T2 hypointensity may result from the tumor cellularity, or from recurrent hemorrhage within the lesion. The solid portions of GCT enhance diffusely after gadolinium administration. Secondary, ABC formation can be seen in about 14 percent of GCT. 17 TUMOR LIKE LESIONS Simple Bone Cyst A bone cyst is a fluid filled lesion with fibrous lining. It occurs in metaphysis of long bones and adjacent to physis in children

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Fig. 23.14: Giant cell tumor—Radiograph of knee (AP and Lat view) show large grossly expansile lytic lesion in lower end of femur, extending up to subchondral region

Fig. 23.16: Aneurysmal bone cyst—Radiograph of shoulder joint shows multiloculated expansile lytic lesion, involving upper end of humerus

Aneurysmal Bone Cyst Aneurysmal bone cyst is solitary, expansile radiolucent lesion and generally located in metaphysis of long bones. Other sites are dorsolumbar spine, small bones of hand, feet and pelvis. Pathologically, the lesion contains multiples cystic spaces containing various stages of blood. Radiologically, the lesion appears as expansile, lytic sharply circumscribed with thin cortex. The characteristic features are its ballooned out appearance and trabeculated appearance (Fig. 23.16). CT may demonstrate fluidfluid level and thin rim of bone overlying the lesion. MRI shows the various stages of blood products which appear as layers of different signal intensity on both T1 and T2W images 18 (Figs 23.17A and B). The differential diagnosis includes giant cell tumor, osteoblastoma, chondroblastoma, osteosarcoma and simple bone cyst.

Fig. 23.15: Bone cyst—Radiograph of knee joint show mildly expansile lytic lesion in metaphysis of tibia with thinning of cortex

and young adults. Common locations are proximal humerus and femur.18 Calcaneum and ileum are less common sites. On plain radiograph, the lesion appears as moderately expansile, well marginated with or without sclerosis (Fig. 23.15). The cortex may be thinned out and may lead to pathological fracture. “Fallen fragment” sign may be seen, when there is piece of bone which migrates into the cavity and settles at the base. CT and MRI can confirm the cystic nature of the lesion. The fluid contents are usually of low intensity on T1-weighted images and hyperintensity on T2-weighted images. However, hemorrhage into the cyst can alter the signal characteristics of the lesion.5,18

Pseudotumor of Hemophilia Hemophilia is a bleeding disorder that occurs in males. Repetitive hemorrhage occurs close to muscle attachments without significant history of trauma. The common locations are iliopsoas and gastrocnemius muscles. Sometimes there is intraosseous or subperiosteal hemorrhage, which can cause pressure erosion of bone. Plain X-ray shows pressure erosion/destruction of bone associated with large soft tissue component (Fig. 23.18A). Calcification within soft tissue hematoma may be seen. MRI shows variable heterogeneous signal, in form of various stages of blood products (Fig. 23.18B). SOFT TISSUE TUMORS The diagnosis of soft tissue tumors in children can be challenging due to broad spectrum of developmental anomalies, neoplasms, inflammatory conditions and pseudotumors. Ultrasonography

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Figs 23.17A and B: Aneurysmal bone cyst—MRI of the same patient, axial T1 and T2W images (A and B) shows well defined multiloculated expansile lesion with fluid-fluid/hemorrhage levels

Figs 23.18A and B: Pseudotumor of hemophilia—Radiograph of lower end of femur: (A) Shows lytic destruction of femur associated with large soft tissue component and bony spicules. MRI of the same patient, fat sat T2WI image (B) Shows large soft tissue with various stages of blood components

(USG) and magnetic resonance imaging (MRI) are extremely useful in the characterization of these tumors. However, an accurate diagnosis can only be made by correlating with the patient’s age, clinical history and physical examination. Ultrasound is usually the modality of choice for the small and superficial soft tissue masses. It has the advantages of relatively low cost, portability, lack of radiation, no need for sedation, and widespread availability. Gray scale imaging should be performed with the highest frequency transducer available. Color Doppler should be performed to demonstrate the presence of vessels within the lesion.

Due to its multiplanar imaging capabilities, high tissue contrast resolution, and lack of radiation, MR imaging is the modality of choice for the evaluation of large and deep masses or for those cases in which US is not adequate. Magnetic resonance imaging (MRI) should include the entire tumor so as to demonstrate its margins. MR images of soft tissue tumors have low specificity, are only occasionally helpful in differentiating between benign and malignant masses with certainty. Some MR imaging criteria have been postulated as indicators of malignancy, particularly in adults. These include size (>5 to 6 cm), absence of low signal on T2-weighted images, signal heterogeneity on

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T1-weighted images, early contrast enhancement, peripheral or heterogeneous enhancement, rapid initial enhancement followed by a plateau or a washout phase, and invasion of adjacent bone, neurovascular bundles, or both.19

Vascular Lesions Vascular lesions are the commonest cause of soft tissue masses in children. Mulliken and Glowacki,20 divided them in two groups based on the findings on physical examination, clinical evolution, histology, and cellular kinetics: Hemangiomas and vascular malformations. Hemangiomas are neoplastic lesions, whereas vascular malformations are errors of vascular morphogenesis. Categorization of a lesion into one of these two groups has significant implications for a patient’s management and prognosis. Hemangioma Hemangiomas are considered to be true neoplasms and they account for 7 to 10 percent of all benign soft tissue tumors.20 Hemangiomas may be localized or diffuse and are histogically benign. Capillary (usually cutaneous), cavernous, venous and mixed types of hemangiomas have been described and classified according to the apparent origin of their vascular channels. Hemangiomas also contain variable amounts of nonvascular tissue and other elements, including fat, smooth muscle, fibrous tissue, myxoid stroma and hemosiderin. USG, CT, MRI and radiolabelled red cell scintigraphy, can facilitate preoperative diagnosis. Radiographs are important for detecting associated osseous abnormality, and the finding of calcified pheleboliths on radiographs or CT images is an indication of a hemangioma (Figs 23.19A and B). Ultrasound shows hemangioma as a well defined mass of variable echogenicity.21 Color Doppler may show high flow pattern in proliferative phase however vascularity decreases in involuting phase. On T1-weighted MRI images, hemangiomas are either isointense or when they contain sufficient fat, hyperintense to muscle. On T2-weighted images, the lesions are well defined and markedly hyperintense with serpiginous high signal zones, that correlate with torturous vascular channels interlaced with lower intensity fibrous or fatty tissue. Phleboliths are hypointense on both T1 and T2-weighted sequences. Hemangiopericytoma is a rare soft tissue tumor of low but unpredictable malignant potential that is believed to arise from vascular endothelial pericytes. These tumors are usually located in the thigh or the pelvic retroperitoneum but can arise in any part of the body. Approximately, 10 percent of hemangiopericytomas occur during childhood, and about one-third of these are congenital.22 Congenital hemangiopericytoma can exhibit rapid initial growth, but spontaneous regression has also been reported. Microscopically, these tumors show endothelial proliferation with some similarity to hemangioma. Calcifications may be detected radiographically or by CT, and the tumors are well circumscribed. There may be partial destruction of adjacent bone. Hemangiopericytomas are very vascular lesions and show marked enhancement and frequently, central necrosis on contrast enhanced CT images.

Figs 23.19A and B: Hemangioma – Radiograph of shoulder joint (A) shows large soft tissue around the joint with phleboliths. MRI of same patient (B) shows large lobulated soft tissue with multiple phleboliths

Like most soft tissue sarcomas, hemangiopericytomas are isointense to muscle on T1-weighted images and exhibit high signal intensity on T2-weighted and STIR images and they enhance moderately with gadolinium.

Vascular Malformations Vascular malformations occur due to errors in vascular development that are always present at birth. Based on the main vascular channel present within the lesion, they are classified as arteriovenous, venous, lymphatic, capillary, or mixed. Arteriovenous malformations are high-flow vascular malformations characterized by direct communication between the arterial and venous systems without an intervening capillary bed. These

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lesions may be detected at birth (40% of cases) and grow commensurately with the child.23 On US, they appear as multiple dilated tortuous channels diffusely involving subcutaneous soft tissues, which may not be apparent on gray scale but are easily demonstrated with color Doppler evaluation. These lesions have a high vascular density, and spectral Doppler analysis reveals high velocity in the arteries, but well-defined mass is usually not seen.21 On MR imaging, they appear as enlarged vascular channels associated with dilated feeding and draining vessels and without an associated well-defined mass. The high-flow vessels appear as signal void foci on spin echo images or as high signal intensity on flow-enhanced gradient-echo images. Venous malformations are characterized by the presence of anomalous ectatic venous channels. They may be small and localized or extensive. On US, venous malformations are usually of heterogeneous echogenicity, more commonly hypoechoic in comparison with the adjacent subcutaneous tissues phleboliths, may be present in 16 percent of cases. Doppler US usually detects slow venous flow within these lesions, although absence of flow is not uncommon which may reflect very slow flow or thrombosis. On MR imaging, they may appear as dilated tortuous veins or more often as lobulated masses, comprised of multiple locules reflecting dilated venous spaces separated by thin interstitial septa. They are iso- to hypointense to muscle on T1-weighted images, hyperintense on T2-weighted images, and show patchy enhancement after the administration of intravenous gadolinium.24 Lymphangioma usually visible at birth, is more frequent in the head and neck but also seen in the trunk, extremities, and in viscera. It may present clinically as, soft, smooth, translucent masses. On US, the macrocystic lymphatic malformations appear as well-defined, multicystic lesions. On MR imaging, the macrocystic lymphatic malformations appear as clearly defined cysts usually of low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, often with fluid-fluid levels. Postcontrast images show only septal enhancement without enhancement of the cystic spaces. This is a helpful feature in the differentiation from venous malformations.24

FIBROBLASTIC/MYOFIBROBLASTIC TUMORS Fibroblastic/myofibroblastic tumors comprise a large number of mesenchymal tumors with both fibroblastic and myofibroblastic features. Common lesions of this group are described here. Nodular Fasciitis Nodular fasciitis is an idiopathic, self-limited focal fibrous proliferation, usually confined to the subcutaneous tissues. Common locations include the upper extremities and trunk. On US, nodular fasciitis is a well-defined lesion with, homogeneous/ heterogeneous echotexture. The MR imaging appearance is variable, although more commonly, it appears as a fascia-based lesion of homogeneous isointense or slightly hyperintense to muscle on T1-weighted images, hyperintense on T2-weighted images, and homogeneous enhancement after gadolinium administration.25

Fig. 23.20: Myositis ossificans – Radiograph of pelvis shows soft tissue ossification adjacent to superior aspect of right acetabulum

Myositis Ossificans Myositis ossificans is a localized, self-limited, reparative hypercellular lesion, composed of reactive hypercellular fibrous tissue and bone. In most cases, a clear history of trauma is obtained. It often occurs in an area exposed to trauma, more commonly in the thighs and arms. Plain X-ray can show heterogeneous calcification, adjacent to bony attachment (Fig. 23.20). CT is the modality of choice for the evaluation of myositis ossificans. The appearance of the lesion changes with time. In the first 2 weeks after trauma, it appears as a noncalcified hypodense mass, with edema of surrounding soft tissues. Curvilinear peripheral calcification becomes evident after 4 to 6 weeks, with progressive internal ossification over the next several weeks and months.26 Myofibroma/Myofibromatosis Solitary myofibroma is a common, benign fibrous tumor commonly seen in children < 2 years of age. It may present as a solitary nodule in the subcutaneous tissues or muscle or as multiple nodules involving soft tissues and bone. The multicentric presentation is known as myofibromatosis. The natural history of myofibromatosis is spontaneous regression; however, a high mortality is reported in multicentric cases with visceral involvement. On US, myofibromas have varied appearances but are often well marginated with an anechoic center, reflecting central necrosis, which can be traversed by thick septa.27 On MR imaging; myofibromas appear as nodules of low signal intensity on T1weighted images and a more variable appearance on T2-weighted images. Fibromatosis Fibromatosis is a benign proliferation of fibroblasts and myofibroblasts with a marked production of collagen. It is

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Fig. 23.22: Plexiform Neurofibroma – MRI of leg shows large lobulated heterogeneous signal intensity lesion involving skin and deep soft tissue of leg.

masses less than 5 cm in diameter. They are isointense to muscle on T1 and heterogeneous signal on T2-weighted images and may show target pattern.29 Plexiform neurofibroma is a diffuse mass involving multiple fascicles of nerve. These lesions can be deep, superficial or combination of both, depending upon the location of tumor. Superficial types of lesions are more common, diffuse and asymmetric in distribution and extend to skin surface (Fig. 23.22).

Adipocytic Tumor Common adipocytic tumors are lipoma, lipoblastoma, and lipomatosis of nerve in the pediatric age group. Liposarcoma, which is the most common type of soft tissue sarcoma in adults is rare in children. Figs 23.21A and B: Fibromatosis – CT scan axial section (A) and coronal reformation (B) shows large soft tissue mass in the lower part of neck extending into axilla with erosion of adjacent scapula

characterized by infiltrative growth and a propensity for local recurrence. These tumors are variably echogenic on ultrasound and their borders may be smooth or irregular. CT scan is useful to show extent of soft tissue and bony erosion (Figs 23.21A and B). On MR images, their appearance is also variable with a signal that is isointense or slightly hyperintense when compared with that of muscle on T1-weighted images and either intermediate between muscles and fat or high signal on T2-weighted images.28

Neurogenic Tumor Most common neurogenic tumor arising from peripheral nerves in children is neurofibroma. Three types of neurofibroma has been described, localized, diffuse and plexiform type.29 Localized neurofibroma are usually well defined, encapsulated soft tissue

Lipoma Lipoma is the most common adipocytic tumor in children, it is often found in the upper back, neck, proximal extremities, and abdomen. Lipomas are usually subcutaneous, although deep ones are not rare, and these will more often require imaging. On US, lipomas have a variable appearance, with about two thirds of cases demonstrating homogeneous echogenicity and 60 percent with well-defined margins. The echogenicity is varied with hypoechoic, isoechoic, hyperechoic, and mixed echogenicity patterns reported. 30 On MR imaging, lipomas have similar signal characteristics compared with subcutaneous fat, characterized by high signal intensity on T1-weighted images and low signal intensity on fat-suppressed images (Fig. 23.23). Lipoblastoma Lipoblastoma is a tumor composed of mature adipocytes and lipoblasts in various stages of development. It represents up to 30 percent of adipocytic tumors in children.31 It occurs primarily

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Fig. 23.23: Lipoma – MRI, axial section (T1W image) of shows well defined lesion in anterior compartment of arm with similar signal intensity of subcutaneous fat

Fig. 23.25: Hematoma – Ultrasound image shows ill-defined heterogeneous echotexture lesion with in the deep muscles of thigh, suggestive of hematoma

Pseudotumors Pseudotumors are non-neoplastic lesions and can present as soft tissue mass. These include hematoma, fat necrosis, inflammatory lesions and periarticular cysts. Fat Necrosis It is self-limiting entity and presents as small non-tender subcutaneous nodule. The causes of fat necrosis include cold exposure, trauma, injection, autoimmune disorders and vasculitis. Common locations include the soft tissues overlying bone prominences in the shoulders, back, buttocks, thighs, and cheeks. Imaging findings on ultrasound is quite variable, however, predominantly it is a hyperechoic nodule with fuzzy margins. Fat necrosis appears as linear shaped abnormal signal in subcutaneous tissue which is usually hypointense on T1 and hypo/hyperintense on T2-weighted images.33

Fig. 23.24: Lipoblastoma – MRI, axial section (T1 W images) of upper thigh, shows large soft tissue mass in left upper thigh with signal intensity of fat as well as soft tissue

in children < 3 years of age and commonly manifests as a painless, progressively growing mass. On US, lipoblastoma usually appears as a homogeneous, hyperechoic mass, although mixed echogenicity and fluid-filled spaces have also been reported. On MR imaging, the appearance reflects the amount of mature adipose tissue relative to lipoblasts and myxocollagenous stromal tissue. They can appear similar to lipoma. When the myxoid component is large the MR signal is heterogeneous and shows contrast enhancement. This imaging appearance is indistinguishable from liposarcoma (Fig. 23.24).32

Hematoma Imaging of hematoma is usually not required, however, it may be indicated in very symptomatic cases, in children without clear history of trauma and in bleeding disorders to know extent of involvement. The imaging appearance of hematoma depends on the age of blood. Ultrasound is the initial investigation of choice. In acute stage, hematoma is hyperechoic however it becomes anechoic/heterogeneous in few days (Fig. 23.25). MRI is useful and it can show hyperintensity on T1-weighted images, hypointense on T2-weighted images and blooming on GRE sequences.34 Inflammatory Lesions Cellulitis occasionally presents as soft tissue mass. Ultrasound shows increased echogenecity of subcutaneous fat. On MRI, cellulitis appears as illdefined T1 hypointense and T2 hyperintense

Chapter 23 ™ Benign Bone and Soft Tissue Tumors and Conditions 393

seen.36 Synovial cyst is lined by synovial cells. Synovial cyst may communicate with joint space. Typical example of synovial cyst is popliteal cyst. Collection of fluid in the meniscus or parameniscal tissue is called meniscal cyst (Fig. 23.27). It is associated with meniscus tear. MR imaging shows well defined cyst/fluid collection in continuity with meniscus tear.37

CONCLUSION A wide spectrum of benign bone and soft tissue tumor and conditions is seen in children. It is imperative for the radiologist to be aware of entire gamut of imaging findings, so as to avoid unwarranted biopsies and surgeries in these children. Plain radiograph continue to be first line imaging modality of choice and is the cornerstone in diagnosis of pediatric benign bone tumors. MR imaging has emerged to become an integral part of diagnostic algorithm of these lesions, owing to its excellent soft tissue resolution, multiplanar capabilities and nonionizing nature. Fig. 23.26: Abscess—Ultrasound image shows well defined collection in subcutaneous soft tissue with internal echoes suggestive of abscess

Fig. 23.27: Meniscal cyst—MRI, coronal section of knee shows tear of meniscus with large adjacent fluid collection communicating with tear suggestive of meniscal cyst

area seen in subcutaneous tissue. Sometimes, aggressive infection leads to abscess formation in soft tissue. On ultrasound, abscess appears as hypoechoic fluid collection (Fig. 23.26). MRI shows, well defined T1 hypointense and T2 hyperintense lesion with peripheral enhancement on postcontrast images.35

Periarticular Cysts These include ganglion, synovial cyst and meniscal cyst. Ganglion is cystic lesion which has fibrous capsule and composed of mucoid material. Imaging (USG and MRI) shows typical features of cyst, however, sometimes internal echoes and septae can be

REFERENCES 1. Fletcher BD. Benign and malignant bone tumor.In Caffey’s Pediatric Diagnostic Imaging Volume 2, Mosby, Elsevier, Philadelphia, 2004. 2. Biermann JS: Musculoskeletal neoplasms in children. In: Orthopaedic knowledge update. Sponseller PD, Shaughnessy JW, (Eds): Rosemont, IL: American Academy of Orthopaedic Surgeons 2002; 51-61. 3. Giudici MA, Moser RP, Kransdorf MJ. Cartilaginous bone tumor. Radiol Clin of North Am 1993; 31:237-59. 4. Mirra JM, Picci P, Gold RH. Bone tumors: Clinical, radiologic and pathologic correlation.Philadelphea, Lea and Fabiger, 1989. 5. Steven S, Srinivas K, Javicr B. MR imaging of tumors and tumor like lesions of upper extremity. Magn. Reson imaging Clin of N America 2004; 12:349-59. 6. Holtz P, Sundaram M. Enchondroma. Orthopedics 1995; 18:50910. 7. Mermelstein LE, Friedlaender GE, Katz LD. Chondroblastoma. Orthopedics 1997; 20:67-71. 8. McGrory BJ, Inwards CY, Mcleod RA, et al. Chondromyxoid fibroma. Orthopadedics 1995; 18(3):307-10. 9. Bloem JL, Kroon HM. Osseous lesions. Radiol clin of North America 1993; 31(2):261-65. 10. Assoun J, Riichardi G, Railhac JJ, et al. Osteoid osteoma: MR Imaging versus CT Radiology 1994; 191:217-36. 11. Bruners P, Penzkofer T, Günther RW, Mahnken A. Percutaneous radiofrequency ablation of osteoid osteomas: Technique and results. Rofo 2009; 181(8):740-7. 12. Moulton JS, Bvaley SE, Biedel JS. Bone and soft tissue tumors. In clinical Magnetic resonance imaging (2nd edn) 1996; 2042-77. 13. Lucas E, Sundaram M, Boccini T. Polyostotic fibrous dysplasia. Orthopaedics 1995; 18(3):311-3. 14. Zeanah WR, Hudson TM. Springfield DS. Computed tomography of ossifying fibroma of the tibia. J Comput Assist Tomogr 1983; 7:688-91. 15. Marin C, Warrier RP. Langerhan’s cell histiocytosis. Orthop Clin of North Am 1996; 27(3):615-23. 16. Copley L, Dormans JP. Benign pediatric bone tumors. Evaluation and treatment. Pediatr Clin North Am 1996; 43:949-66. 17. Murphey MD, Nomikos GC, Flemming DJ, et al. Imaging of giant cell tumor and giant cell reparative granuloma of bone: Radiologicpathologic correlation. Radiographics 2001; 21:1283–309.

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18. Conway WF, Hayes CW. Miscellaneous lesions of bone. Radiol Clin of North Am 1993; 31(2):339-58. 19. Brisse H, Orbach D, Klijanienko J, Fre´neaux P, Neuenschwander S. Imaging and diagnostic strategy of soft tissue tumors in children. Eur Radiol 2006; 16(5):1147-64. 20. Mulliken JB, Glowacki J. Hemangiomas and vascular malformations in infants and children: A classification based on endothelial characteristics. Plast Reconstr Surg 1982; 69(3):412-22. 21. Paltiel HJ, Burrows PE, Kozakewich HPW, Zurakowski D, Mulliken JB. Soft-tissue vascular anomalies: Utility of US for diagnosis. Radiology 2000; 214(3):747-54. 22. Auguste LJ. Razack MS, Sako K. Hemangiopericytoma. J Surg Oncol 1982; 20:260-4. 23. Frieden I, Enjolras O, Esterly N. Vascular birthmarks, other abnormalities of blood vessels and lymphatics. In: Schachner LA, Hansen RC, eds. Pediatric Dermatology. 3rd edn. New York, NY: Mosby 2003; 833-62. 24. Konez O, Burrows PE. Magnetic resonance of vascular anomalies. Magn Reson Imaging Clin N Am 2002; 10(2):363-88. 25. Leung LYJ, Shu SJ, Chan ACL, Chan MK, Chan CHS. Nodular fasciitis: MRI appearance and literature review. Skeletal Radiol 2002; 31(1):9-13. 26. Siegel MJ. Magnetic resonance imaging of musculoskeletal soft tissue masses. Radiol Clin North Am 2001; 39(4):701-20. 27. Koujok K, Ruiz RE, Hernandez RJ. Myofibromatosis: Imaging characteristics. Pediatr Radiol 2005; 35(4):374-80.

28. Lee JC, Thomas JM, Phillips S, Fisher C, Moskovic E. Aggressive fibromatosis: MRI features with pathologic correlation. AJR Am J Roentgenol 2006; 186(1):247-54. 29. Stull MA, Moser RP, Kransdorf MJ, et al. Magnetic resonance appearance of peripheral nerve sheath tumors. Skeletal Radiol 1991; 20:9-14. 30. Fornage BD, Tassin GB. Sonographic appearances of superficial soft tissue lipomas. J Clin Ultrasound 1991; 19(4):215-20. 31. Miller GG, Yanchar NL, Magee JF, Blair GK. Lipoblastoma and liposarcoma in children: An analysis of 9 cases and a review of the literature. Can J Surg 1998; 41(6):455-8. 32. Murphey MD, Carroll JF, Flemming DJ, Pope TL, Gannon FH, Kransdorf MJ. From the archives of the AFIP: Benign musculoskeletal lipomatous lesions. Radiographics 2004; 24(5):1433-66. 33. Tsai TS, Evans HA, Donnelly LF, Bisset GS III, Emery KH. Fat necrosis after trauma: A benign cause of palpable lumps in children. AJR Am J Roentgenol 1997; 169(6):1623-6. 34. Bush CH. The magnetic resonance imaging of musculoskeletal hemorrhage. Skeletal Radiol 2000; 29(1):1-9. 35. Faingold R, Oudjhane K, Armstrong DC, Albuquerque PAB. Magnetic resonance imaging of congenital, inflammatory,and infectious soft-tissue lesions in children. Top Magn Reson Imaging 2002; 13(4):241-61. 36. Seymour R, Lloyd DCF. Sonographic appearances of meniscal cysts. J Clin Ultrasound 1998; 26(1):15-20. 37. McCarthy CL, McNally EG. The MRI appearance of cystic lesions around the knee. Skeletal Radiol 2004; 33(4):187-209.

chapter 24

Pediatric Malignant Bone and Soft Tissue Tumors Manisha Jana, Ashu Seith Bhalla, Deep N Srivastava INTRODUCTION Malignant bone tumors account for about 6 percent of all childhood malignancies;1,2 though malignant soft tissue tumors are rare in childhood. The most common malignant bone tumors include osteosarcoma and Ewing’s sarcoma, while rhabdomyosarcoma is the commonest pediatric malignant soft tissue tumor.3,4 Most of the tumors affect the appendicular skeleton and result in significant morbidity and mortality. Table 24.1 shows age distribution of these tumors. IMAGING MODALITIES Plain Radiographs Radiographs are the primary imaging modality in cases of bone tumors, and often a specific diagnosis can be made on plain radiographs alone depending on location of the lesion (Table 24.2). The appearance of the lesion and the patient age remain important considerations for diagnosis. Most of the pediatric malignant bone tumors involve the metaphysis, however, Ewing’s sarcoma and lymphoma have a propensity to involve diaphysis. The pattern of bone destruction is a pointer towards the aggressiveness of the lesion. Most malignant bone tumors present radiographically with a permeative lytic or moth-eaten pattern of bone destruction (Fig. 24.1). In cases of pediatric soft tissue tumors, plain radiographs are often of limited importance. Clinical examination can often prove useful in evaluating small superficial lesions (e.g. lipoma), but for proper assessment of extent of most soft tissue tumors, radiologic evaluation is imperative. Sonography Ultrasonography is useful for characterization of some lesions especially for superficial lesions.5 Doppler can help in the assessment of vascularity of lesion and also for guided biopsies and in monitoring tumor response to chemotherapy. Computed Tomography (CT) Among the cross sectional imaging, role of CT has considerably reduced after the introduction of MRI. However, CT is superior to MRI in the detection and characterization of matrix mineralization,

bone trabeculation and periosteal reaction. CT is also used in the detection of pulmonary metastases.

Magnetic Resonance Imaging (MRI) The role of magnetic resonance imaging in pediatric bone tumors include accurate assessment of the extent of the lesion, evaluation of skip lesions, neurovascular and articular involvement. T1W spin echo images remain the most important sequence to assess the tumor extent, owing to the contrast between normal hyperintense fatty marrow and hypointense tumor.6 Inversion recovery sequence Table 24.1: Age distribution of pediatric bone and soft tissue tumors Age

Bone Tumor

Soft Tissue Tumor

Less than 5 years

- Osteosarcoma - Ewing’s sarcoma - Lymphoma

-

Rhabdomyosarcoma Infantile fibrosarcoma Hemangiopericytoma Granulocytic sarcoma

More than 5 years

-

-

Rhabdomyosarcoma Synovial sarcoma Granulocytic sarcoma Hemangiopericytoma

Osteosarcoma Ewing’s sarcoma Lymphoma Malignant fibrous histiocytoma (rare) - Chondrosarcoma (rare)

Table 24.2: Common locations of primary malignant bone tumors Location

Tumors

Metaphysis

-

Diaphysis

- Ewing’s sarcoma - Lymphoma

Epiphysis

- Aggressive giant cell tumor (rare)

Osteosarcoma Metastases Ewing’s sarcoma Lymphoma Malignant fibrous histiocytoma

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Fig. 24.1: Plain radiograph of the left leg shows permeative lytic destruction, periosteal reaction (white arrow) and Codman triangle (black arrow), typical imaging features of a malignant bone tumor. Histopathology: osteosarcoma

(short tau inversion recovery—STIR) sequence makes the tumor more conspicuous by suppressing normal marrow fat as the hyperintense tumor stands bright. Postcontrast images (after Gadolinium administration) can define the exact extent of the tumor, define viable tumor and the necrotic areas7 and help in tumor edema differentiation. 8 Peritumoral edema can either be intraosseous or extraosseous and often show high signal on T2 weighted or STIR images. In the bones, edema has poorly defined margin and often difficult to differentiate from the tumor mass. In the soft tissues, edema does not have mass effect and follows muscle and fascial planes. Most of the malignant bone and soft tissue tumors share common similar imaging features, e.g. they are hypointense on T1W and hyperintense on T2W images.9-12 However, few lesions show characteristic signal intensities, e.g. fat containing lesions are bright on T1W as well as T2W sequences and fibrous tumors may show hypointense signal on both T1 as well as T2W images. The differentiation of benign from malignant nature of a mass is not possible in most cases on MR imaging; but the useful role of MRI is in tumor staging.

MRI Techniques for Bone and Soft Tissue Tumors The sequences should include T1W images in coronal or sagittal plane for accurate delineation of tumor extent (Fig. 24.2A) and articular involvement, if any. T2W fat saturated or STIR images is useful for better demonstration of relationship with adjacent muscles, nerves and vascular structures (Fig. 24.2B). Role of Contrast-enhanced MRI In primary bone and soft tissue tumors, contrast administration is often not required. However, T1W fat saturated images are helpful in follow-up imaging for detection of recurrence. Dynamic contrast-

Figs 24.2A and B: Sagittal T1W (A) and T2W (B) MR of a case of osteosarcoma. The tumor is hypointense in contrast to hyperintense fatty marrow on T1W and hyperintense on T2W sequences. The tumor has an extra compartmental extension into the muscle plane (Stage T2)

enhanced MRI is specifically helpful in detecting tumor recurrence,13 which often shows early contrast enhancement and washout.

Newer MR Imaging Techniques Diffusion weighted MRI: Diffusion weighted MRI has been used to predict the tumor viability after treatment, and hence, to reflect the response to treatment. After treatment many a times the tumor bulk may not reduce significantly but the apparent diffusion coefficient (ADC) value increases14 indicating response to treatment. Dynamic Contrast-enhanced MRI: Dynamic contrast-enhanced MRI is a new addition in the imaging of malignant bone tumors,

Chapter 24 ™ Pediatric Malignant Bone and Soft Tissue Tumors

especially osteosarcoma. It measures the tumor viability by determining the contrast accumulation within the tumor. Dynamic contrast-enhanced MRI assessment of dynamic vector magnitude (based on contrast accumulation rate over time and maximal intensity of the tumor) and Kep (measure of the gadolinium exchange between the vascular and the interstitial space) tend to predict the outcome after treatment.15 MR spectroscopy: In vivo proton MR spectroscopy is a promising modality in the evaluation of malignant bone and soft tissue tumors. On MR spectroscopy these tumors show choline peak (resonance at 3.2 ppm);16 which is highly sensitive and specific.

Staging of Malignant Bone and Soft Tissue Tumors The Enneking system of staging malignant bone and soft tissue tumors17 (Table 24.3) was based on three criteria: extent of tumor (T1 suggests an intracompartmental tumor, T2 an extracompartmental spread (Figs 24.2A and B)), presence or absence of metastases (M0 and M1 respectively) and histologic grade of the tumor (low grade G1, high grade G2). Low grade tumors (stage IA or IB; T1G1M0 or T2G1M0) are candidates for wide local excision or limb salvage surgeries. High grade tumor (G2) without metastases are treated with radical surgeries like amputation. In 1983, AJCC developed another system of staging of bone and soft tissue tumors depending on four criteria: extent of tumor (confined by bone cortex T1; with transcortical extension T2), nodal disease (N0 no nodal disease; N1 regional nodal spread), metastases (absence of metastases M0; presence of metastases M1) and histologic grade of tumor (G1-well differentiated tumor, G2moderately differentiated, G3-poorly differentiated and G4 undifferentiated). The recent revision in this staging is based on the size of the tumor rather than transcortical extension ( T1 tumors being less than 8 cm and T2 more than 8 cm).18 A new stage T3 has been added to indicate skip matastases. These classification system did not include bone lymphoma or myeloma. MALIGNANT BONE TUMORS Osteosarcoma Osteosarcoma is the most common pediatric malignant bone tumor,19 usually affecting children in the second decade. Patients with retinoblastoma, Li-fraumeni syndrome, prior radiation therapy are more prone to develop osteosarcoma. The usual clinical presentation is with a painful mass. Histologic subgroups in osteosarcoma include osteoblastic, chondroblastic, fibroblastic, giant cell rich, telangiectatic or small cell type.20 Plain radiographs are usually the first investigation performed. Osteosarcoma in pediatric age groups predominantly involve the metaphyses. On radiographs they present with a permeative lytic destruction with wide zone of transition (Fig. 24.1), blastic lesion (Fig. 24.3) or a mixed pattern. Often there is an associated soft tissue component, ‘sunburst’ type of periosteal reaction, ‘Codman triangle’ formation (Fig. 24.1); and an osteoid tumor matrix

397

Table 24.3: Enneking staging for primary malignant bone tumors Stage

Tumor

Metastases

Histologic grade

IA IB IIA IIB III

T1 (intracompartmental tumor) T2 (extracompartmental tumor) T1 T2 T1 or T2

M0 M0 M0 M0 M1

G1 G1 G2 G2 G1 or G2

Fig. 24.3: Lateral radiograph of the knee in a child with osteosarcoma of the tibia. The tumor shows dense osteoid matrix mineralization

mineralization (Fig. 24.3). Pathological fractures are more common in a telangiectatic variety. The work-up of a child with osteosarcoma include computed tomography (CT) of chest (Figs 24.4A to C), 99mTc MDP bone scan (to detect metastases as it spreads via the bloodstream and about 20 percent may have metastases at presentation)6 and MRI for the local tumor extent. MRI tends to show accurate intramedullary extent of the tumor. Tumor mass is usually hypointense on T1W and hyperintense on T2W and STIR images (Fig. 24.5). The rare telangiectatic variety shows blood-fluid levels secondary to intratumoral hemorrhage3 (Fig. 24.6). Skip lesions within the same bone, may be seen in 15 percent of cases. Survival and response to chemotherapy depends on the tumor burden which can be measured by tumor size. Histologic response to preoperative neoadjuvant chemotherapy (percent of necrosis) is the strongest predictor of survival.21-23 Often the tumor size remains unchanged after treatment and it is difficult to determine response based on the size criteria.15 Newer MR imaging techniques which help in predicting tumor response include diffusion weighted images and dynamic contrast-enhanced MRI. With treatment, the apparent diffusion coefficient (ADC) of the

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Fig. 24.5: Axial T2W fat saturated MR image in a case of telangiectatic osteosarcoma showing multiple areas of blood-fluid levels (white arrow) suggesting intratumoral hemorrhage

Fig. 24.6: PNET of the right femur. Axial CT scan bone window reconstruction reveals mixed lytic-sclerotic destruction of the right femoral head and neck with adjacent large soft tissue

tumor mass increases.14 Dynamic contrast-enhanced MRI assessment of dymanic vector magnitude (based on contrast accumulation rate overtime and maximal intensity of the tumor) and Kep (measure of the gadolinium exchange between the vascular and the interstitial space) tend to predict the outcome after treatment.15 Figs 24.4A to C: Coronal T1W (A) and axial T2W fat saturated (B) MR of a case of osteosarcoma showing the craniocaudal and axial extent of the marrow involvement. The tumor has extracompartmental extension into the muscle plane (Stage – T2). Axial CT thorax (lung window) (C) of the same patient show multiple lung metastases

Ewing’s Sarcoma Ewing’s family of tumors include classic Ewing’s sarcoma, primitive neuroectodermal tumor (PNET), Askin tumor (PNET of the chest wall), extraosseous Ewing’s tumor and peripheral

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399

Fig. 24.7: Ewing’s sarcoma. Axial CT bone window reconstruction reveals permeative lytic destruction of the femoral diaphysis, with spiculated periosteal reaction (arrows) and associated soft tissue

neuroepithelioma. All these tumors have a common neuroectodermal origin and frequently seen in children. Classic Ewing’s sarcoma is the second most common bone malignancy in children, predominantly seen in the second decade of life. Males and females have equal incidence. Usual clinical presentation is with local pain and swelling; often with constitutional symptoms. Laboratory investigations may show elevated erythrocyte sedimentation rate and leukocytosis; hence the picture often mimics osteomyelitis. Metadiaphyses of the long bones are the most common site for Ewing’s sarcoma. On plain radiographs, the tumor presents as a permeative lytic bone destruction with a wide zone of transition; cortical destruction; onion-peel type of periosteal reaction and often extensive noncalcified soft tissue mass.24 Saucerisation of the outer cortex may occur due to erosions by tumor growth in the subperiosteal region. In cases of flat bone involvement, the soft tissue component is larger than osseous destruction. CT scan, though not commonly indicated, can define the bony destruction (Fig. 24.7). However, chest CT is done to detect pulmonary metastasis. Radionuclide study is useful in the detection of bone metastasis. The differential diagnosis includes osteomyelitis. On T1W MRI the mass is isointense to mildly hypointense; on T2W or STIR images it is hyperintense (Figs 24.8A and B) and shows variable contrast enhancement. Skip lesions may be present in 14 percent cases.24 The soft tissue mass tends to decrease in size and undergo necrosis with treatment. As with osteosarcoma, diffusion weighted MRI and dynamic CE-MRI can predict the response to neoadjuvant chemotherapy or radiotherapy.23 Positron emission tomography (PET) is also used in monitoring response to therapy and metastatic disease. PNET of the chest wall (Askin tumor) (Fig. 24.9) usually presents with an intrathoracic extrapulmonary mass having rib involvement

Figs 24.8A and B: Sagittal T1W (A) and Coronal T2W (B) MR of a case of Ewing’s sarcoma. The tumor is hypointense on T1 and heterogeneously hyperintense on T2 with diffuse marrow infiltration and extraosseous spread

and extrathoracic component. They are hypointense on T1W and hyperintense on T2W images, showing moderate contrast enhancement. Multiplanar imaging using MRI or CT is helpful in determining the extent of the soft tissue mass.

Chondrosarcoma Chondrosarcoma is rare in pediatric age group, and should be differentiated from the chondroblastic variety of osteosarcoma. It predominantly involving the long bones of pelvis and shoulder girdle followed by metaphyses of long bones, ribs and spine. The tumors can either be primary or secondary. On radiographs they are usually expansile lytic lesions with variable matrix mineralization (chondroid type). On MR imaging they show low

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Fig. 24.9: PNET of the left thoracic wall (Askin tumor). Axial image of CECT thorax mediastinal window shows a large heterogeneous mass lesion in the left hemithorax with a small extrathoracic component

Fig. 24.10A: NHL of the left thoracic wall. Chest radiograph reveals opaque left hemithorax with lytic sclerotic destruction of left 7th and 8th ribs as well as the 8th dorsal vertebral body

signal intensity on T1W images. The signal on T2W images are variable, depending on the matrix. Cartilaginous matrix is bright on T2WI whereas areas of calcification and hemorrhage are hypointense.25

Lymphoma Primary bone lymphoma comprises of 5 percent of all children with lymphoma and most of them are high grade B-cell NHL.20 Usual locations include the spine and the long bones. On imaging, they commonly show permeative lytic destruction, sometimes with periosteal reaction and commonly associated with soft tissue component. Frank cortical destruction is often not evident, and the lesions are easily missed on radiographs.26 Hodgkin’s disease can cause sclerotic bony lesions and ‘ivory’ vertebra. MRI reveals the marrow of the affected bone to be hypointense on T1W and hyperintense on T2W images, enhancing after contrast (Figs 24.10A and B). Secondary bone lymphoma is commoner than primary bone lymphoma, especially in children. The incidence can be as high as 25 percent in children. Secondary skeletal involvement in Hodgkin’s disease is usually from contiguous lymph nodal spread, and the lesions are more commonly sclerotic. In secondary involvement by non-Hodgkin’s lymphoma, most commonly affected sites are pelvis, spine and skull. The usual presentation is with permeative lytic destruction of bone with cortical destruction. Metastases Metastases to bone in pediatric age group commonly occurs from primary tumors like neuroblastoma, Ewing’s sarcoma or neuroblastoma. Osseous metastases in osteosarcoma are usually blastic. Metastases from neuroblastoma show a ‘sunburst’ type of periosteal reaction. When occurring in the calvarium, they often give rise to sutural diastasis secondary to dural deposits.

Fig. 24.10B: Axial CECT bone window of the same patient shows permeative lytic sclerotic bone destruction involving the vertebral body, posterior element and the posterior ribs having a large soft tissue component in the paraspinal locations and along posterolateral thoracic wall

Malignant Fibrous Histiocytoma Malignant fibrous histiocytoma occurs very rarely in pediatric age group, and usually affects the adolescents. Most common location includes metaphysis of a long bone. The radiographic findings range from geographic to permeative lytic destruction. Periosteal reaction is uncommon,27 unlike other malignant tumors. MRI features are non-specific.

Chapter 24 ™ Pediatric Malignant Bone and Soft Tissue Tumors

SOFT TISSUE TUMORS In the pediatric age group, most of the soft tissue masses are benign; only 1-6 percent being malignant.28 Rhabdomyosarcoma alone comprises more than half of the pediatric soft tissue sarcomas.3,4 In the 0-5 years age group, fibrosarcoma is the commonest and in 6-15 years age group, malignant fibrous histiocytoma, synovial sarcoma and rhabdomyosarcoma are common.29 MR imaging often cannot accurately determine the benignity or malignant nature of a soft tissue mass, but some indicators which favor a benign etiology include younger age group, smaller size of the mass, well circumscribed lesion, subcutaneous or fascial location, homogeneous signal on T2W imaging and no surrounding edema.30 Sometimes, a malignant soft tissue tumor may have well defined margins with a pseudocapsule and homogeneous in signal intensity on MRI. The prime important role of imaging in soft tissue tumor is not to provide an accurate diagnosis but to provide information regarding the extent of tumor, extension beyond fascial planes, adjacent bone and neurovascular bundle involvement. Other important role of imaging include response assessment after treatment. Differentiating a residual or recurrent tumor from posttreatment changes is the most challenging part in follow-up imaging. Both can present with high T2W signal intensity. Tumor recurrence is often associated with mass effect and contrast enhancement; whereas post-treatment changes lack these features.31 Rhabdomyosarcoma Rhabdomyosarcoma (Figs 24.11 and 24.12) accounts for 4-5% of all childhood cancers and 10-15 percent of solid tumors in the extremities.32 The most common locations are the head and neck region, genitourinary tract, the retroperitoneum and the extremities. The histologic subtypes include embryonal, alveolar and the undifferentiated types. The alveolar subtype, which is relatively aggressive, is seen in the extremities. The prognosis of this tumor depends on the size, local invasion, nodal spread and distant metastases. Tumors with a diameter less than 5 cm has better overall prognosis. Extremity tumors, which are usually of alveolar subtype, have a poorer prognosis. Prognosis is better in case of proximal extremity tumors than distal tumors.33 Complete resection is the treatment of choice and survival in unresectable tumors is poor. On MR imaging, the tumor is isointense to muscle on T1W and hyperintense on T2W images and shows strong contrast enhancement.30 Synovial Sarcoma Synovial sarcoma (Figs 24.13A and B) is the most common nonrhabdomyosarcomatous soft tissue sarcoma in the children. It is a high grade tumor showing differentiation of tumor cells into spindle cells resembling synoviocytes; and not derived from synovial cells. The usual location of this tumor is in periarticular regions, though it can occur in other places. These tumors commonly present as a painless extremity mass, most commonly around the knee joints. On imaging, they are well defined, lobulated in outline, isointense to muscle on T1W and heterogeneously hyperintense on T2W images, with areas of hemorrhage.34 Scattered calcification is seen

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Fig. 24.11: Rhabdomyosarcoma in a child presenting with rapid onset proptosis and facial swelling. CECT orbit coronal reformatted image shows a large heterogeneously enhancing mass lesion causing destruction of the left zygoma and lateral maxillary and orbital wall

Fig. 24.12: Rhabdomyosarcoma in a child presenting with an enlarging back mass. Axial CECT abdomen shows infiltration of the mass into the paraspinal and posterior abdominal muscles on right side

in as high as one-third of the lesions.35 Sometimes the lesions are cystic, mimicking a ganglion cyst or Baker’s cyst.28

Other Non-rhabdomyosarcomatous Tumors Other non rhabdomyosarcomatous tumors are rare in childhood and include fibrosarcoma, hemangiopericytoma, granulocytic sarcoma, malignant fibrous histiocytoma, epithelioid sarcoma and clear cell sarcoma. The peak age group affected by infantile fibrosarcoma is below 5 years, specifically in infants or neonates. These are usually large

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Fig. 24.14: Granulocytic sarcoma in a case of acute myeloid leukemia. CECT of head reveals multiple enhancing soft tissue masses (arrows) involving the calvarium

Figs 24.13A and B: Synovial sarcoma in a 15-year-old. CECT thigh axial soft tissue window and (A) and (B) Coronal maximum intensity projection (MIP) images show a heterogeneous mass lesion in the extensor compartment, abutting and displacing the right superficial femoral artery

disfiguring masses, but biologic behavior is favorable than their adult counterparts. They rarely metastasize. They are isointense to muscles on T1W images and heterogeneously hyperintense on T2W images.36 Contrast enhancement is usually heterogeneous. In older children the tumor behaves like those in adults, with a more aggressive course.4 Granulocytic sarcoma (also called chloroma) is seen in 5% cases of acute myeloid leukemia and contains primitive precursors of granulocytes. To begin with, they arise in bone marrow and traverses the haversian canals to extraosseous locations. The most common site in head and neck region (Fig. 24.14). They are isointense to muscle one as well as T2W images, showing homogeneous enhancement.37

CONCLUSION Though the pediatric malignant bone tumors account for about 6% of all childhood malignancies, malignant soft tissue tumors are rare in childhood. The role of imaging is to assess the extent of the lesion, thus establishing the accurate stage and determining resectability. Plain radiographs are the most important tool in evaluating bone tumors. MRI offers better assessment of the bony and extraosseous extent and neurovascular involvement, the knowledge of which is crucial for surgery. CT scan of thorax and bone scans are required to determine the presence or absence of metastases. Soft tissue lesions in childhood are usually benign. The primary role of imaging is to assess the extent in a soft tissue lesion, thus establishing the accurate stage and determining resectability. REFERENCES 1. Wootton-Gorges SL. MR imaging of primary bone tumors and tumor-like conditions in children. Radiol Clin N Am 2009; 47:95775. 2. Caudill JSC, Arndt CAS. Diagnosis and management of bone malignancy in adolescence. Adolesc Med 2007; 18:62-78. 3. Arndt CA, Crist WM. Common musculoskeletal tumors of childhood and adolescence. N Engl J Med 1999; 341(5):342-52. 4. Miser JS, Pizzo PA. Soft tissue sarcomas in childhood. Pediatr Clin North Am 1985; 32(3):779-800. 5. Stein-Wexler R. MR imaging of soft tissue masses in children. Radiol Clin N Am 2009; 47:977-95. 6. Hoffer FA. Primary skeletal neoplasms: Osteosarcoma and Ewing sarcoma. Top Magn Reson Imaging 2002; 13:231-400. 7. Meyer JS, Nadel HR, Marina N, et al. Imaging guidelines for children with Ewing sarcoma and osteosarcoma: A report from the children’s oncology group bone tumor committee. Pediatr Blood Cancer 2008; 51:63-70.

Chapter 24 ™ Pediatric Malignant Bone and Soft Tissue Tumors 8. Alyas F, James SL, Davies AM, et al. The role of MR imaging in the diagnostic characterization of appendicular bone tumors and tumor-like conditiond. Eur Radiol 2007; 17:2675-86. 9. Berquist TH, Ehman RL, King BF, et al. Value of MR imaging in differentiating benign from malignant soft-tissue masses: Study of 95 lesions. AJR Am J Roentgenol 1990; 155(6):1251-5. 10. Kransdorf MJ, Murphy MD. Radiologic evaluation of soft-tissue masses: A current perspective. AJR Am J Roentgenol 2000; 175(3):575-87. 11. Soler R, Castro JM, Rodriguez E. Value of MR findings in predicting the nature of soft tissue lesions: Benign, malignant or undetermined lesion? Comput Med Imaging Graph 1996; 20(3):163-9. 12. Jelinek J, Kransdorf MJ. MR imaging of soft-tissue masses. Mass like lesions that simulate neoplasma. Magn Reson Imaging Clin N Am 1995; 3(4):727-41. 13. Woude HJ, Bloem JL, Verstraete KL, Taminiau AH, et al. Osteosarcoma and Ewing’s sarcoma after neoadjuvant chemotherapy: Value of dynamic MR imaging in detecting viable tumor before surgery. AJR Am J Roentgenol 1995; 165:593-98. 14. Hayashida Y, Yakushiji T, Awai K, et al. Monitoring therapeutic responses of primary bone tumors by diffusion-weighted image: initial results. Eur Radiol 2006; 16:2637-43. 15. McCarville MB. New frontiers in pediatric oncologic imaging. Cancer Imaging 2008; 8:87-92. 16. Wang C-K, Li C-W, Hsieh T-J, Chien S-H, Liu G-C, Tsai K-B. Characterization of bone and soft-tissue tumors with in vivo 1H MR spectroscopy: Initial results. Radiology 2004; 232:599-605. 17. Enneking WF, Spanier SS, Goodman MA. A system for surgical staging of musculoskeletal sarcoma. Clin Orthop 1980; 153:10620. 18. American Joint Committee on Cancer, Bone. In: Greene FL, Page DL, Fleming ID, et al, (Eds): AJCC Cancer Staging Manual. New York, NY. Springer-Verlag, 2002; 213-19. 19. Longhi A, Errani C, De Paolis M, et al. Primary bone osteosarcoma in the pediatric age: State of the art. Cancer Treat Rev 2006; 32:42336. 20. Vlychou M, Athanasou N. Radiological and pathological diagnosis of pediatric bone tumours and tumour-like lesions. Pathology 2008; 40(2):196-216. 21. Reddick WE, Wang S, Xiong X, et al. Dynamic magnetic resonance imaging of regional contrast access as an additional prognostic factor in pediatric osteosarcoma. Cancer 2001; 91:2230-7. 22. Bacci G, Ferrari S, Bertoni F, et al. Histologic response of highgrade nonmetastatic osteosarcoma of the extremity to chemotherapy. Clin Orthop Relat Res 2001; 386:186-96.

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23. Provisor AJ, Ettinger LJ,Nachman JB, et al. Treatment of nonmetastatic osteosarcoma of the extremity with preoperative and postoperative chemotherapy: A report from the Children’s cancer Group. J Clin Oncol 1997; 15:76-84. 24. Peersman B, Vanhoenakcker FM, Heyman S, et al. Ewing’s sarcoma: Imaging features. JBR-BTR 2007; 90:368-76. 25. Kaim AH, Hugli R, Bonel HM, et al. Chondroblastoma and clear cell chondrosarcoma: radiological and MRI characteristics with histopathological correlation. Skeletal Radiol 2002; 31:88-95. 26. Krishnan A, Shirkhoda A, Tehrznzadeh J, et al. Primary bone lymphoma: Radiographic-MR imaging correlation. Radiographics 2003; 23:1371-87. 27. Murphey MD, Gross TM, Rosenthal HG. Musculoskeletal malignant fibrous histiocytoma: Radiologic-pathologic correlation. Radiographics 1994; 14:807-26. 28. Bissett GS 3rd. MR imaging of soft-tissue masses in children. Magn Reson Imaging Clin N Am 1996; 4(4):696-719. 29. Kransdorf MJ. Malignant soft-tissue tumors in a large referral population: Distribution of diagnoses by age, sex and location. AJR Am J Roentgenol 1995; 164(1):129-34. 30. Moulton JS, Blebea JS, Dunco DM, et al. MR imaging of soft tissue masses: Diagnostic efficacy and value of distinguishing between benign and malignant lesions. AJR Am J Roentgenol 1995; 164(5):1191-9. 31. Siegel MJ. Magnetic resonance imaging of musculoskeletal soft tissue masses. Radiol Clin North Am 2001; 39(4):701-20. 32. Kim EE, Valenzuela RF, Kumar AJ, et al. Imaging and clinical spectrum of rhabdomyosarcoma in children. Clin Imaning 2000; 24(5):257-62. 33. Tabrizi P, Letts M. Childhood rhabdomyosarcoma of the trunk and extremities. Am J Orthp 1999; 28(8):440-6. 34. Jones BC, Sundaram M, Kransdorf MJ. Synovial sarcoma: MR imaging findings in 34 patients. AJR Am J Roentgenol 1993; 161(4):827-30. 35. Frassica FJ, Khanna JA, McCarthy EF. The role of MR imaging in soft tissue tumor evaluation: Perspective of the orthopaedic oncologist and musculoskeletal pathologist. Magn Reson Imaging Clin N Am 2000; 8(4):915-27. 36. Eich GF, Hoeffel JC, Tschappeler H, et al.Fibrous tumors in children: Imaging features of a heterogeneous group of disorders. Pediatr Radiol 1998; 28(7):500-09. 37. Stein-Wexler R, Wootton-Gorges SL, West DC. Orbital granulocytic sarcoma: An unusual presentation of acute myelocytic leukemia. Pediatr Radiol 2003; 33(2):136-9.

SECTION 6—CENTRAL NERVOUS SYSTEM

chapter 25

Congenital Brain Anomalies N Khandelwal INTRODUCTION Congenital malformations of the brain are numerous with over 2000 malformations described so far. Its incidence is reported to be about 1 percent of all live births. About 60 percent of cases have no known etiology while 40 percent may have chromosomal inheritance or acquired cause. Approximately 75 percent of fetal deaths are attributed to these malformations.1 Congenital malformations result from abnormal formation of the brain structure during intrauterine development.2,3 Various classifications have been proposed. Table 25.1 shows the broad subgroups. Table 25.1: Classification of congenital brain anomalies I. Disorders of organization (Due to arrest of brain development and with normal histogenesis) A. Supratentorial 1. Migrational disorders Lissencephaly Hemimegalencephaly Heterotopias Schizencephaly Polymicrogyria 2. Holoprosencephaly 3. Syndrome of septo-optic dysplasia 4. Dysgenesis of corpus callosum 5. Hydranencephaly B. Infratentorial anomalies 1. Dandy-Walker complex 2. Cerebellar aplasia/ hypoplasia 3. Chiari malformation C. Both intratentorial and supratentorial anomalies 1. Cephalocele 2. Arachnoid cyst II. Disorders of Histogenesis (Result from persistent development of abnormal cells in the otherwise normally structured brain) 1. Neurofibromatosis 2. Tuberous sclerosis 3. Sturge-Weber syndrome 4. Von Hippel-Lindau disease 5. Ataxia-telangiectasia * Adapted from Byrd and Charles2

DISORDERS OF ORGANIZATION Supratentorial Malformations Migrational Disorders Lissencephaly or smooth brain: In this condition, there is complete or partial absence of sulcation. Complete lack of gyri is termed as agyria and the presence of few, broad and flat gyri is termed as pachygyria. Patient of lissencephaly presents with dysmorphic facies, seizures, mental retardation and microcephaly. Sonographic findings include a smooth surfaced cortex without sulcal or gyral formation. Sonography can only suggest the diagnosis of lissencephaly but the characteristic findings are more readily identifiable on CT or MRI. Based on CT and MRI, three types of lissencephaly have been described: a. Classic (type I) lissencephaly (4-layer lissencephaly) b. Cobblestone (type II) lissencephaly (congenital muscular dystrophy) and c. Lissencephaly not otherwise classified. Classic lissencephaly is further divided into 3 subcategories based on associated genetic abnormalities namely: i. Deletion of the LIS 1 gene on chromosome 17 ii. An X-linked lissencephaly and iii. An indeterminate subset with neither of the above chromosomal abnormalities. In classical lissencephaly,4 the MRI features are that of an abnormal contour and surface of the brain. The cerebral surface is smooth, devoid of sulci (agyric) or with few areas of pachygyria or with equal areas of pachygyria and agyria. The brain assumes a figure of 8 appearance due to the bilateral shallow sylvian fissures. There is marked reduction in the white matter, the gray white matter interface is smooth with loss of cortical white matter distribution5 (Figs 25.1A and B). Hemimegalencephaly or unilateral megalencephaly: This condition may be idiopathic or may be associated with contralateral somatic hemihypertrophy, linear sebaceous nevus syndrome, neurofibromatosis NF1.4 The affected cortex is typically dysplastic with broad gyri, shallow sulci and cortical thickening. Gyral pattern may appear grossly normal. It may be associated with lissencephaly or polymicrogyria. There is an indistinct differentiation between the cortex and subcortical white matter. The ipsilateral lateral ventricle is enlarged with the frontal

Chapter 25 ™ Congenital Brain Anomalies 405

Fig. 25.2A: Hemimegalencephaly: axial CT scan shows overgrowth of the left hemisphere giving asymmetrical appearance of the brain

(double cortex) (Figs 25.3C and D) which appears as a homogeneous gray matter band between the cerebral cortex and the lateral ventricle. It is characteristically surrounded by a zone of white matter. The cortex overlying the heterotopia is nearly always abnormal with pachygyria or polymicrogyria.

Figs 25.1A and B: Lissencephaly: Short TR axial MR sections in two patients showing the shallow sylvian fissures giving a figure of eight configuration of the cerebral hemispheres. Note the thickened cortex better delineated in B

horn directed anterosuperiorly (Figs 25.2A to C). Rarely brain has a bizarre, hamartomatous appearance. Heterotopias: Heterotopias are the least severe of all the migrational disorders. The term denotes presence of normal neural tissue at an abnormal location secondary to arrest of neuronal migration along the radial glial fibers.4 The abnormally located gray matter is isointense with cortical gray matter in all MR imaging sequences and this is a diagnostic feature. Heterotopias are of two types: the common, nodular type (Figs 25.3A and B) is characterized by multiple masses of gray matter which are of variable size. They are commonly located in the subependymal region of the lateral ventricles or in the subcortical white matter. The second type is the uncommon band or lamellar heterotopia

Schizencephaly or split brain: It is a form of migrational disorder characterized by abnormal columns of gray matter across the cerebral hemisphere. The basic abnormality is a pial-ependymal seam (gray matter lined cleft) which extends across full thickness of cerebral hemisphere from the ventricular system (ependyma) to the periphery (pial surface) of the brain. These clefts are usually perisylvian but can occur anywhere in the brain. Two types have been described: • Type I or closed lip schizencephaly is characterized by a gray matter lined pial ependymal seam with both the lips apposed to each other. There is no intervening CSF cavity. The common site of involvement is the roof or lateral borders of lateral ventricle. MR or CT scan will show an outpouching or nipple at the ependymal surface of the cleft in closed lip schizencephaly. MRI demonstrates the full thickness of cleft and the pial-ependymal seam of gray matter (Figs 25.4A and B). • Type II or open lip schizencephaly in which the pial ependymal seam is widened by a CSF cleft. CT and MRI shows the CSF cleft extending from the ventricular system to the pial surface of brain. The CSF cavity is usually bilateral and symmetric. However, it may be asymmetric or even unilateral. Severe form of open lip schizencephaly presents with massive CSF cavities which communicate with the ventricular system and has an appearance which is a called “basket brain”. This congenital malformation has a high association with absence of septum pellucidum, polymicrogyria, septo-optic dysplasia, heterotopia4 (Figs 25.4C and D).

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There are three types of holoprosencephaly—alobar, semilobar and lobar. Prenatal ultrasound, and postnatal CT or MRI can image the confluent ventricles and thalami adequately: a. Alobar holoprosencephaly is the most severe form of holoprosencephaly. There is no differentiation of the frontal, occipital or temporal lobes. The cerebral hemispheres are fused to form a small flat mass of tissue containing single crescent shaped holoventricle. The flattened cerebrum occupies a small rostral segment of the calvarium. The calvarium is occupied with the large dorsal cyst which communicates with the holoventricle. Thalami may be fused with absence of interhemispheric fissure, falx cerebri and septum pellucidum. The cerebellum and brainstem are relatively normal. This condition is associated with a severely dysmorphic facies, abnormal reflexes and increased tone at birth. b. Semilobar holoprosencephaly (Fig. 25.5A) is a less severe form of holoprosencephaly. There is partial separation of the cerebral hemispheres with rudimentary temporal and occipital lobes. The frontal lobes are fused. There is a monoventricle with presence of the falx cerebri which is only partially seen posteriorly and suggestion of presence of an interhemispheric fissure. Septum pellucidum is absent and thalami are partially separated. The splenium of the corpus callosum is formed without the genu or body (Fig. 25.5A). c. Lobar holoprosencephaly (Fig. 25.5B) is the least severe form. Brain appears normal but the frontal horns remain fused with absence of septum pellucidum. Appearance of the frontal horns with angular corners is termed “box-like”. Temporal and occipital horns are separated and are of normal size and shape. However, the bodies of the lateral ventricles may be closely apposed. Interhemispheric fissure is formed but is shallow anteriorly. The thalami are separated.

Figs 25.2B and C: Hemimegalencephaly: T1W1 shows unilateral megalencephaly with a larger left hemisphere. Note the larger left lateral ventricle (B) and the prominent sulcation of that hemisphere (C)

Holoprosencephaly Holoprosencephaly is a congenital malformation characterized by incomplete cleavage and differentiation of the prosencephalon (forebrain) into cerebral hemispheres. Mutation of at least 4 different genetic loci have been identified to be associated with this condition and these are on chromosome 21, 2, 7 and 18. Syndromic association of this condition are encountered in trisomy 13 (Patau’s syndrome) and trisomy 18 (Edwards’ syndrome). Embryogenesis of holoprosencephaly is postulated to be the lack of mesenchyme in the developing rostral neural tube, as a result of which the telencephalon does not separate from the diencephalon. The telencephalon does not develop in the two hemispheres and there is lack of cortical organization.6

Septo-optic Dysplasia Septo-optic dysplasia is believed to be a mild form of lobar holoprosencephaly and consists of absence of septum pellucidum with hypoplasia of the optic nerve and optic chiasma and hypoplasia of the hypothalamus. MRI shows these findings with clarity. In addition abnormally squared or flattened frontal horns of the lateral ventricles and an enlarged anterior recess of the third ventricle may be seen. It may be associated with aqueductal stenosis, Chiari II malformation, schizencephaly, and corpus callosum agenesis. In addition, an association of hypothalamus pituitary dysfunction is seen in two-thirds of the patients with this condition.7 Dysgenesis of Corpus Callosum The corpus callosum is a midline commissure that crosses from one cerebral hemisphere to the other. The corpus callosum develops in the cephalocaudal direction with the genu developing at 2.5 months of gestation followed by the body and splenium. The rostrum is the last to develop. Adult configuration is achieved by 5th month of gestation.8 In corpus callosum agenesis, genu is usually present but body and splenium are dysgenic.

Chapter 25 ™ Congenital Brain Anomalies 407

Figs 25.3A and B: Nodular heterotopia: Coronal IR (A) and axial T1W (B) images showing undulating layer of gray matter lining the lateral ventricles

Figs 25.3C and D: Lamellar heterotopia: Axial T1 WI (A) and coronal IR image (B) shows a band of gray matter in the periventricular region which is isointense with the cortex

Diagnostic features on imaging are parallel nonconverging lateral ventricles, dilated occipital horns (colpocephaly) (Fig. 25.6). The third ventricle is widended and is placed between the lateral ventricles. If the dilated third ventricle reaches the interhemispheric fissure it is referred to as dorsal interhemispheric cyst (Fig. 25.6B). Midsagittal MR scan readily demonstrates absence of the corpus callosum. Cingulate sulcus is absent and the gyri appear to radiate from a high riding third ventricle (Fig. 25.6D). Presence of Probst bundle (longitudinally oriented tracts) cause indentation on the medial aspect of the lateral ventricles which appear concave medially on coronal MR sections.2 Coexisting congenital malformations are common which include Dandy-Walker complex, arachnoid cyst, cephalocele and colobomas. Aicardi syndrome is association of corpus callosum

agenesis, infantile spasms and ocular abnormalities and is especially seen in females.2,5

Hydranencephaly Hydranencephaly is an encephaloclastic porencephaly which results presumably secondary to in utero occlusion of either of the internal carotid arteries, or infection such as CMV or due to a genetic cause. This results in infarction, necrosis and destruction of the cerebral cortex. The cerebral hemispheres are replaced by a thin-walled membranous sac which is lined by glial tissue on the inside and leptomeninges on the outside. Diagnosis on ultrasound is easy as the falx cerebri, thalami and cerebellar hemispheres are identified in the presence of the two large fluidfilled sacs.2

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Figs 25.4A to D: Schizencephaly: Closed lip: Axial (A) and sagittal (B) T1 W MR sections show deep extension of cerebral sulci reaching uptil the ventricle with gray matter lining. Open lip : Axial CT (B) and T1 MR (D) sections show bilateral CSF clefts communicating with the lateral ventricles

Differential diagnosis includes severe hydrocephalus, in which a rind of remaining cortical mantle can be identified, and alobar holoprosencephaly where absence of falx and presence of fused thalami clinches the diagnosis. CT or MRI may be done when US findings are equivocal (Figs 25.7A and B).

Infratentorial Malformations Dandy-Walker (DW) complex: This includes Dandy-Walker malformation, Dandy-Walker variant and the mega cisterna magna.9 This represents the morphological spectrum of fundamental anomalous cerebellar vermis and adjacent cerebellar hemispheres. The cerebellar vermis is usually hypoplastic with atresia of the outlet of fourth ventricle, resulting in abnormal dilatation of 4th

ventricle with expansion of posterior fossa (Fig. 25.8). There is consequently superior displacement of the tentorium and dural sinuses. Skull radiographs show expansion of posterior cranial fossa, thinning and ballooning of occipital bone and upward displacement of lateral sinus groove which indicates elevation of tentorium. Sonographic features of Dandy-Walker complex include anechoic posterior fossa cyst, small cerebellar hemispheres, elevated tentorium and hydrocephalus. CT and MRI are helpful to show the structures in their proper perspective. Multiplanar imaging of MRI is superior to CT for demonstrating the anatomy. Diagnostic criteria of DW complex on CT/MR are as follows:

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Fig. 25.5A: Semilobar holoprosencephaly: Axial CT section shows a monoventricle with a dorsal cyst and partially formed temporal lobes

Fig. 25.5B: Lobar holoprocencephaly: Axial short TR sequence MR section shows fused frontal horns of the lateral ventricles. The cerebral hemisphere are well formed however the anterior interhemispheric fissure is partially delineated

a. Dandy-Walker malformation is characterized by absence of or hypoplasia of the cerebellar vermis. There is associated hypoplasia of the cerebellar hemispheres giving a characteristic winged appearance to these hemispheres. The fourth ventricle is enlarged and opens dorsally into a CSF containing cyst. The posterior fossa is enlarged with a high insertion of the tentorium consequently the transverse sinuses are higher in position than normal. Eighty percent of patients have associated hydrocephalus. Associated anomalies include corpus callosum agenesis (20-25%), heterotopias, polymicrogyria, occipital cephaloceles and schizencephaly.9 b. In Dandy-Walker variant, there is varying degree of inferior vermian and cerebellar hypoplasia. The retrocerebellar CSF

collection communicates with normal or mildly enlarged 4th ventricle via a prominent vallecula. The tentorial position and size of posterior fossa are normal. Coronal images through posterior fossa may show absence of the vermis. The brainstem is usually normal and hydrocephalus is an uncommon association.7,8 c. Mega cisterna magna is a large subarachnoid cistern lying posterior to the vermis and can extend all the way up to the straight sinus superiorly and the C1-C2 level inferiorly. It may cause scalloping of the inner table of occipital squama, without any compression of the fourth ventricle. One of the differential diagnosis is a retrocerebellar arachnoid cyst, which is a CSF collection within the layers of arachnoid membrane

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Fig. 25.6A: Corpus collosum agenesis: Axial CT sections show parallel configuration of the lateral ventricles. Absence of the corpus callosum leads to separation of the interhemispheric fissure. A shunt has been placed in the right lateral ventricle

Fig. 25.6B: Corpus callosum agenesis associated with an interhemispheric cyst which extends across the midline

Figs 25.6C and D: Corpus callosum agenesis: T1 W sagittal and axial images depicting partial corpus callosum agenesis with parallel alignment of lateral ventricles (colpocephaly) and radiating pattern of cerebral gyri

and does not communicate fully with the subarachnoid or ventricular spaces. The posterior fossa and ventricular system are normal. The fourth ventricle and vermis may be displaced by the cyst.

The Chiari Malformations There are four Chiari malformations10 which represent a spectrum of anomalies of primary neurulation, i.e. those which occur when the brain and upper spine are developing at about 3 to 4 weeks of gestation.

Chiari I malformation (caudal-cerebellar tonsillar ectopia) consists of herniation of elongated peg like cerebellar tonsils through the foramen magnum into the upper cervical spinal canal. Chiari’s original description of this anomaly included associated hydrocephalus, though it is not mandatory for the diagnosis to be made.11 Tonsillar descent has been described in four categories of Chiari I malformation.4 1. This malformation can be associated with abnormal intracranial pressure. Intracranial hypotension due to chronic CSF leaks or associated with CSF shunts can result in ‘sagging

Chapter 25 ™ Congenital Brain Anomalies 411

Figs 25.7A and B: Hydranencephaly vs congenital hydrocephalus: Axial CT section (A) shows presence of a preserved cortical mantle with interhemispheric fissure. Bilateral subdural collection favor the diagnosis of hydrocephalus. In hydranencephaly the brain is replaced by a fluid filled sac (B). No cortical mantle is identified

Figs 25.8A and B: Dandy-Walker malformation: Absent vermis with the fourth ventricle communicating directly with a posterior fossa cyst; winged cerebellar hemispheres are characteristic of this malformation

brain’. Raised intracranial tension due to cerebral edema or intracranial masses can push the tonsils downwards. 2. Chiari I malformation can be seen with platybasia or basilar invagination or craniovertebral anomalies such as persistence of proatlas remnants, shortened clivus and C-1 assimilation. 3. Prenatal or postnatal hydrocephalus can result in Chiari 1 malformation, this subset was included in the original description of the malformation. 4. Asymptomatic tonsillar ectopia with no obvious abnormality has been described and may be congenital. The degree of tonsillar descent is of some importance. Descent less than 5 mm below a line from the basion to the opisthion is considered to be of no clinical significance whereas tonsillary

descent more than 6 mm can be associated with clinical symptoms. Correlation between age of the patient and tonsillar descent is also important. Between the age of 5 to 15 years descent of up to 6 mm is not considered pathologic. In older individuals protrusion more than 5 mm below the foramen magnum is invariably associated with an increasing incidence of symptoms. Association of syringomyelia is another important aspect of Chiari I malformation.12 The incidence reported varies between 25-65 percent. The focus on MR studies which is the mainstay of diagnosis of this condition is to show the degree of tonsillar herniation in midsagittal section, evaluation of the craniovertebral junction, assessment of the lateral ventricles for hydrocephalus and to detect

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Figs 25.9A and B: Chiari I malformation: Midline sagittal long TR MR section (A) showing herniation of the cerebellar tonsil below the foramen magnum. Sagittal MR section of the whole spine (B) shows presence of the associated syrinx of the cervical and dorsal segments of the spinal cord

presence of syrinx in the upper cervical spine. MR CSF flow studies show increased motion of the tonsil and brainstem and decreased CSF flow to the vallecula13 (Figs 25.9A and B). Chiari II malformation is characterized by caudal displacement of the brainstem and inferior part of cerebellum into the upper cervical spinal canal. All patients of Chiari II malformations have a lumbar meningomyelocele. They nearly always develop hydrocephalus after closure of the meningomyelocele for which they are initially imaged when the lesions of the Chiari II malformation are detected.1 These patients can present with epilepsy (17%), dysphagia, apnoeic spells, shoulder or arm weakness, weak cry or stridor. The hind

brain malformations have been best explained in a theory by McLone and Knepper14 who have postulated that the basic anomaly is a small posterior fossa into which a normal sized cerebellum develops. Lack of space within the posterior fossa together with a low lying tentorium forces the brainstem and cerebellum through the enlarged foramen magnum. Sagittal MR scan shows stretching of the pons inferiorly. It is compressed anteroposteriorly. The medulla is pushed inferiorly through the widened foramen. The cervical spinal cord is in turn stretched inferiorly as well. Caudal displacement of the cervical cord is restricted by the dentate ligaments. Therefore, there is kink at the junction of the displaced medulla at the cervicomedullary junction. In severe cases, the cerebellum may wrap around the brainstem. The fourth ventricle is vertically oriented, compressed and displaced inferiorly. The vermis herniates and may be compressed by the superior arch of the C1. The herniated and compressed vermis may degenerate. In severe cases the whole of the cerebellum may atrophy. Beaking of the quadrigeminal plate is probably secondary to the compression by the expanded temporal lobes due to hydrocephalus. Isolation of the fourth ventricle may occur due to aqueductal narrowing and diminished flow through the fourth ventricular outflow foramina. Paradoxically, the fourth ventricle is not dilated, however, the supratentorial ventricles will dilate. In these patients, attempt should be made to look for the presence of syringohydromyelia. Chiari II malformation can be associated with corpus callosum agenesis, enlarged massa intermedia, fenestrated falx cerebri, an abnormal gyral pattern on the medial aspect of the occipital lobe termed as stenogyria.4 The Chiari III malformation includes the feature of the Chiari II malformation with a low occipital or high cervical encephalocele. The encephalocele contains occipital lobes, part of the cerebellum and occasionally medulla and pons. The Chiari IV malformation includes severe cerebellar hypoplasia or absent cerebellum. There is a large posterior fossa CSF space. There is no obstructive hydrocephalus. Detailed evaluations using current imaging methods have introduced more subtle forms of the malformation, currently named as Chiari 0 and Chiari 1.5 which are characterized by altered CSF flow dynamics.8

Supra-and Infratentorial Malformations Cephalocele is a term given to herniation of intracranial contents through defects in the skull.15 If the herniated contents are leptomeninges and CSF, the cephalocele is termed as a meningocele. When one contains brain tissue, leptomeninges and CSF, it is called a meningoencephalocele. Herniation of meninges, brain and ventricles is termed encephalocysto-meningocele. Herniation of intracranial contents occurring through fracture (growing fracture) or through surgical defect is an acquired cephalocele. In South-east Asia the commonest cephaloceles encountered in clinical practice are nasal encephaloceles. Occipital (70%), parietal (10%) frontal (9%) and nasopharyngeal (1%) are the commonest types of encephaloceles encountered in North America and Europe.2

Chapter 25 ™ Congenital Brain Anomalies 413

Fig. 25.10A: Occipital encephocele: Axial CT section shows a defect in the occipital bone with protrusion of the right cerebellar hemisphere through the defect

Fig. 25.10B: Parietal cephalocele: A large right parietal cephalocele containing brain matter, CSF and ectatic enhanced dura

On plain radiograph defects in the calvarium associated with cephaloceles appear well defined with sclerotic margins. If the protrusion of the brain content is large, there is a reduction in the craniofacial ratio. Cross-sectional imaging is necessary to define the contents of the cephalocele. Sonography is a valuable mode of investigation in the prenatal diagnosis of cephaloceles. It can also differentiate whether the cephalocele contains CFS alone or CSF with brain matter. The former appears anechoic and the latter as a complex mass. CT demonstrates the extent of bony defect as well as contents of the cephalocele. MR is the most sensitive and accurate modality to detect and characterise the cephalocele. In addition

multiplanar acquisition helps in the assessment of location of the cephelocele. MR venography is useful to assess the position of superior sagittal sinus and torcular herophili as they may herniate into parietal or occipital encephocele. Frontoethmoidal cephaloceles lie between the nasal and ethmoid bones. They are not associated with neural tube defects. Nasal encephalocele is formed when there is failure of closure of the dural diverticulum in the prenasal space. This diverticulum connects the superficial ectoderm of the developing nose to the developing brain with the cranium. Thus, there can be a large patent opening through which brain matter can herniate or there can be a sinus tract, i.e. dermal sinus or sequestration of heterotopic or dysplastic glial tissue resulting in the so-called nasal glioma. Thus, these lesions appear as soft tissue masses and CSF collections which appear in continuum with intracranial structures. Absence of the crista galli is a constant feature of a cephalocele, alternatively, it can be split by the presence of a dermal sinus or dermoid in this location. Coronal CT scaning is partially useful in demonstrating the bony defects within location. Occipital encephalocele originates between foramen magnum and lambda. It contains variable amount of brain matter which is usually gliotic and non-functional. Association with Chiari II and III malformation is common (Fig. 25.10A). Parietal cephalocele arises between bregma and lambda. Associated anomalies include corpus callosum agenesis, Chiari II malformation and Dandy-Walker complex (Fig. 25.10B). Encephaloceles involving the sphenoid bone are further classified as transsphenoid, transsellar sphenoidal, sphenoethmoidal, sphenomaxillary, spheno-orbital and transethmoidal encehaloceles. These are occult cephalocele with patients presenting with hypertelorism, endocrine dysfunction and mental retardation. They are associated with true clefts of the lip and nose. These cephaloceles protrude through the body of the sphenoid into the nasal cavity or in severe cases, through the palate into the oral

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cavity. They invariably contain parts of the hypothalamus, pituitary gland and the third ventricle.16

DISORDERS OF HISTOGENESIS “Neurocutaneous syndromes” or “Phakomatoses” constitute a group of congenital malformations which are characterized by cutaneous lesions associated with CNS anomalies.17 Prominent amongst these are: 1. Neurofibromatosis/von Recklinghausen’s disease. 2. Tuberous sclerosis/Bourneville disease 3. Sturge-Weber syndrome. 4. von Hippel-Lindau disease 5. Ataxia telangiectasia. Neuroimaging studies are important in the diagnosis of these conditions because based on clinical presentations there are specific diagnostic imaging features in many of the conditions. The diagnosis can almost always be made on MRI because it can differentiate gray and white matter, characterize tumors from hamartomas, show extent of soft tissue lesions through bony defect and to some extent differentiate various vascular anomalies associated with these conditions.15,16

Neurofibromatosis Neurofibromatosis comprises of a group of heterogeneous diseases which have been classified into two groups: Neurofibromatosis 1 (NF 1) and Neurofibromatosis 2 (NF 2). Neurofibromatosis type 1 (NF 1) accounts for 90 percent of cases of neurofibromatosis with an incidence of 1: 2000 to 3000 live births. This autosomal dominant condition occurs due to mutation on the long arm of chromosome 17. The condition is of variable expression and high penetrance. Inactivation of the tumor repressor gene or NF 1 gene is thought to be the genetic basis of the disease. Diagnosis of NF1 is made when two or more of the following findings are present:18,19 • Six or more café-au-lait spots measuring 5 mm or more in largest diameter in pre-pubertal children or 15 mm or more in the post-pubertal period. • One plexiform neurofibroma or two or more neurofibromas of any type. • Two or more pigmented hamartomas (Lisch nodules) of the iris. • Optic nerve glioma • A distinctive osseous lesion such as dysplasia of the sphenoidal wing. • Axillary or inguinal freckling • A first degree relative with NF 1. Optic pathway glioma is the most common CNS lesion in NF1. It is best imaged by MRI which delineates the entire extent of the lesion from the optic nerve, chiasma, optic tract, optic radiation and the lateral geniculate bodies although latter three structures are rarely involved. It is a low grade pilocytic astrocytoma. On MR scan it appears a fusiform lesion which is hypo to iso-intense on T1WI with variable contrast enhancement. The optic canal is enlarged. Other gliomas associated with NF1 involve the brainstem, tectum and periaqueductal white matter.

Fig. 25.11: Neurofibromatosis Type 1: Non-contrast coronal CT showing sphenoid wing dysplasia with intraorbital herniation of the dura

Plexiform neurofibroma is a hallmark of NF1. It is an unencapsulated neurofibroma along the path of a major cutaneous nerve, of the scalp and neck. The commonly involved nerve is the first division of the trigeminal nerve. It is invariably associated with dysplasia of the sphenoid bone and bony orbit (Fig. 25. 11A). On CT scan this lesion appears as low attenuating lesion which generally do not enhance. On MR T1WI they are isointense to muscle and show variable enhancement after contrast administration. Other intracranial lesions include hamartoma, astrocytic proliferation of the retina, intracranial aneurysms, non-aneurysmal vascular ectasias and a progressive cerebral arterial occlusive disease akin to moya-moya pattern.2 Skeletal dysplasias that may occur include calvarial defects, hypoplasia of the sphenoid wing, scoliosis, scalloping the posterior aspects of the vertebral bodies with hypoplasia of the pedicles, spinous and transverse processes. Dural dysplasia and lateral/anterior intrathoracic meningoceles are other associated anomalies.2,16 Neurofibromatosis type 2 (NF-2) is an autosomal dominant entity which is associated with defect in the chromosome 22. Bilateral acoustic nerve schwannomas are the most consistent and hence diagnostic feature of this condition (Figs 25.11A to 25.12B). Cutaneous manifestations include neurofibroma and pale café au lait spots. Skin lesions appear in the first decade of life which are followed by development of acoustic neuromas between the age of 10-15 years. Presence of cataracts and skin lesions in a child are valuable clinical indicators of NF-2. The diagnostic criteria20 for NF-2 include 1. Bilateral eighth nerve schwannoma 2. A first degree relative with NF-2 and a. A unilateral eighth nerve acoustic schwannoma or

Chapter 25 ™ Congenital Brain Anomalies 415

b. Two of the following • Neurofibroma • Meningioma • Glioma • Schwannoma • Juvenile posterior subcapsular opacity or • Cerebral calcification 3. Two of the following • Unilateral vestibular schwannoma • Multiple meningiomas • Features listed under 2b above (Except for meningiomas). Apart from VIIIth nerve schwannoma, the trigeminal nerve, oculomotor nerve, trochlear or the abducens nerve schwannoma are also seen in NF-2. These tend to be isodense to hypodense on CT and shows patchy but significant enhancement after contrast administration. On MR studies schwannoma appear as well delineated masses which are iso-hyperintense on T2WI. Intense patchy enhancement occurs after gadolinium administration. Other forms of neurofibromatosis have been described. They have been labelled as NF 3 to NF 7. An eighth category NF-NOS includes cases which are atypical and do not fit into the labelled categories.19,20 Details of these form of neurofibromatosis are beyond the scope of this chapter. Tuberous sclerosis (TS) is an inherited autosomal dominant condition with a low penetrance. The locus of this condition is identified on two chromosomes. The TSC1 gene is localized to chromosome 9q34 and the TSC2 gene is localized to chromosome 6p13.3 which are associated with hamartoma formations in multiple organ systems.21 The classical triad of papular facial lesions (adenoma sebaceum), seizure disorder and mental retardation are the hallmark of this disease.16 Subependymal hamartomas are the hallmark of tuberous sclerosis. They are located on the ventricular surface of caudate nucleus, immediately posterior to the foramen of Monro and along the frontal and temporal horns of the lateral ventricles. On MR they protrude into the adjacent ventricle. They are hyperintense on T1WI they appear hyper- and hypointense on T2 WI relation to gray and white matter. They show minimal contrast enhancement (Fig. 25.13). Subependymal giant cell astrocytoma (SGCA) are benign tumors associated with TS usually located at the foramen of Monro in about 15 percent. They are hypo to isointense on T1WI and hyperintense on T2WI and enhance uniformly after contrast administration. Cerebral hamartomas are most characteristic. They are low attenuating on CT and with age become calcified. White matter low attenuating, well defined lesions are highly characteristic lesions of TS. Like NF 2, retinal hamartoma, aneurysm and vascular dysplasia have also been described with tuberous sclerosis.2,16 Sturge-Weber syndrome (encephalotrigeminal angiomatosis) is a congenital non-inherited entity. It is a syndrome characterized by angiomatous malformation affecting the skin, eye and brain. The typical lesion is a facial angioma (port wine stain) in the

Figs 25.12A and B: Neurofibromatosis Type 2: Contrast enhanced axial T1 section (A) shows enhancing CP angle masses with intracanalicular extension consistent with B/L acoustic schwannomas (A). The enhancing tentorial based lesion is a meningioma (B)

distribution of all the divisions of the trigeminal nerve. It is usually unilateral and there is concomitant involvement of the ipsilateral occipital lobe, parietal lobes, and choroid plexus. Ocular findings of buphthalmos, optic atrophy, iris heterochromia and strabismus may be encountered. Patients may present with hemiparesis, homonymous hemianopia and seizures. The vascular malformations are low-pressure, slowly-flowing leptomeningeal angiomata. There is a congenital absence of cortical veins, therefore the blood is shunted towards the hypertrophied deep medullary veins and thence to the choroid plexus. The relatively static venous flow leads to hypoxia of the affected cortex which inturn leads to cortical atrophy and dystrophic calcification (Fig. 25.14) which can be demonstrated

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Figs 25.13A to C: Tuberous sclerosis: Contrast enhanced T1 axial MR sections showing subependymal nodules in two patients (A,B) alongwith cortical tubers on FLAIR coronal sections (C)

Fig. 25.14: Sturge-Weber syndrome: Non-contrast CT scan shows subcortical calcification with atrophy of the affected left parietal and occipital lobes. Calcification is also present in the right occipital lobe

Chapter 25 ™ Congenital Brain Anomalies 417

Figs 25.15A and B: Sturge Weber syndrome: A 4-year-old presented with a nevus flammeus on the left half of face. (A) Contrast enhanced CT shows diffuse cortical calcification on both frontal lobes and atrophy of left temporal and occipital lobe. (B) Enhancement of prominent choroid plexus and temporal angioma (curved arrows) can be appreciated

on plain X-ray and CT. The resulting curvilinear calcification is diagnostic of the syndrome. It is commonly seen in the occipital and posterior parietal lobe on the side of the facial angioma. If there is extensive atrophy, there is marked dilatation of the ipsiventricle, thickening of the calvarium and prominence of the ipsilateral paranasal sinuses which are obvious on plain radiograph. The ipsilateral choroid plexus is enlarged and may contain cysts and enhance intensely. The pial angiomas can show enhancement on both MR and CT (Fig. 25.15).22 The abnormal venous channels of the cortex and subependymal location can be identified on angiograms or MRI. Thus, congenital malformations of the CNS includes a large number of diverse conditions. CT and especially MRI has a very important role to play in characterizing the lesions which help in establishing the diagnosis. MR imaging has been used extensively in recent years to investigate the neuroanatomical basis of congenital brain malformations. Newer techniques like diffusion imaging including diffusion tensor imaging (DTI) and high angular resolution diffusion imaging (HARDI) have helped in fiber tractography and have elucidated the aberrant connectivity underlying a number of congenital brain malformations.23 They however still remain in the research arena and will take time to come to the clinical field.

REFERENCES 1. Osborn AG. Brain development and congenital malformation. In Osborn AG (Ed): Diagnostic Neuroradiology St Louis: Mosby Year Book 1994; 3-116. 2. Byrd SE, Charles RF. Congenital brain malformations. In Khun JP, Slovis TL, Haller JO (Eds): Caffey’s Pediatric Diagnostic Imaging (10th edn). St. louis: Mosby Year Book 2004; 506-29.

3. Barkovich AJ, Kuzhiecky RI, Dobyns WB, et al. A classification scheme for malformations and cortical development. Neuropediatrics 1996; 27:59-63. 4. Abdel Razek AA, Kandell AY, Elsorogy LG, Elmongy A, Basett AA. Disorders of cortical formation: MR imaging features. AJNR Am J Neuroradiol 2009; 30:4-11. 5. Robertson R, Casuso PA, Truwit CL. Disorders of brain development. In Atlas SW (Ed): Magnetic Resonance Imaging of the Brain. Philadelphia: Lippincott Williams and Wilkins 2002; 279369. 6. Hahn JS, Barnes PD. Neuroimaging advances in holoprosencephaly: Refining the spectrum of the midline malformation. Am J Med Genet C Semin Med Genet 2010; 15:120-32. 7. Morishima A, Aranoff G. Syndrome of septo-optic pituitary dysplasia: The clinical spectrum brain dev 1986; 8:233-35. 8. Paul LK, Brown WS, Adolphs R, Tyszka JM, Richards LJ, Mukherjee P, Sherr EH. Agenesis of the corpus callosum: genetic, developmental and functional aspects of connectivity. Nat Rev Neurosci 2007; 8:287-99. 9. Altman N, Naidich T, Braffman B. Posterior fossa malformation AJNR Am J Neuroradiology 1992; 13:691-724. 10. Vannemreddy P, Nourbakhsh A, Willis B, Guthikonda B. Congenital Chiari malformations. Neurol India 2010; 58(1):6-14. 11. Kollias S, Ball W, Prenger E. Cystic malformations of the posterior fossa, differential diagnosis classified through embryologic analysis. Radiographics 1993; 13:1211-31. 12. Chiari H, Uber Veranderungen des Kleinhirns, des Pons unde der. Medulla oblongata infolge von congenitaler hydrocephalie des Gross hirns Denkschr Kais Akad Wiss Mathnaturew 1896; 63:71-116. 13. Bhaddelia RA, Bogdan AR, Wolpert SM. Analysis of cerebrospinal fluid flow waveforms with gated phase contrast MR velocity measurements. AJNR AM J Neurorad 1995; 10:389-400. 14. McLone DG, Knepper PA. The cause of Chiari II malformaiton. A unified theory. Pediatr Neuroscience 1989; 15:1-12.

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15. Naidich T, Altman N, Braffman B, et al. Cephaloceles and related malformations AJNR, Am J Neuroradiology 1992; 13:655-90. 16. Smirniotopoulous JG, Murphy FM. Central nervous system manifestations of the phakomatoses and other inherited syndromes. In Atlas SW (Ed): Magnetic Resonance Imaging of Brain and Spine (3rd edn). Philadelphia: Lippincott Williams and Wilkins 2002; 371-413. 17. Barkovich AJ. The phakomatoses. In: Barkovich AJ. Pediatirc Neuroimaging. 4th edn. Philadelphia: Lippincott Williams and Wilkins 2005; 476–81. 18. Neurofibromatosis, conference statement. National Institutes of Health Consensus Development Conference. Arch Neurol 1988; 45:575-78.

19. Mulvihill JJ. (moderator) Neurofibromatosis I (Recklinghausen’s disease) and Neurofibromatosis 2 (bilateral acoustic neurofibromatosis) an update. Ann Inter Med 1990; 113:39-52. 20. Ricardi VM. Neurofibromatosis. Neurol Clin 1987; 5:337-49. 21. Orlova KA, Crino PB. The tuberous sclerosis complex. Ann N Y Acad Sci 2010; 1184:87-105. 22. Stimac GK, Solomon MA, Newton TH. CT and MR of angiomatous malformations of the choroids plexus in patients with Sturge–Weber disease. AJNR, Am J Neuroradiology 1986; 7:623-27. 23. Wahl M, Barkovich AJ, Mukherjee P. Diffusion imaging and tractography of congenital brain malformations. Pediatr Radiol 2010; 40:59-67.

chapter 26

Hypoxic-Ischemic Encephalopathy Atin kumar, Arun Kumar Gupta

Neonatal encephalopathy following birth asphyxia or perinatal hypoxia is referred to as hypoxic-ischemic encephalopathy (HIE).1 HIE is a common clinical problem with far reaching consequences. It, therefore, becomes mandatory for the pediatrician and the pediatric radiologist to understand its etiology, pathology, pathophysiological mechanism and imaging features with awareness of the limitations and advantages of each imaging modality. Exact incidence of HIE is not known but at most centers incidence of perinatal hypoxic-ischemia is between 1.0 to 1.5 percent.2 Clinically HIE has been graded into mild, moderate and severe grades with prognosis directly related to the severity.3 Approximately 15 to 20 percent of neonates with hypoxic ischemia would die within the newborn period.4

BELOW 34 WEEKS GROUP – THE PREMATURE NEONATE Preterm neonates are much more prone to HIE than term neonates. It occurs because of increased chances of hypoxic insult due to very low birth weight (